x	ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

¨	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

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•	adverse economic or political conditions in the U.S. and international markets;

•	competition in the wireless services market, including new competitors entering the industry as technologies converge;

•	the effects any future merger or acquisition involving us, as well as the effects of mergers or acquisitions in the technology, media and telecommunications industry;

•	challenges in implementing our business strategies or funding our wireless operations, including payment for additional spectrum or network upgrades;

•	the possibility that we may be unable to renew our spectrum licenses on attractive terms or acquire new spectrum licenses at reasonable costs and terms;

•	difficulties in managing growth in wireless data services, including network quality;

•	material changes in available technology;

•	the timing, scope and financial impact of our deployment of advanced network and business technologies;

•	the impact on our networks and business from major technology equipment failures;

•	breaches of our and/or our third party vendors’ networks, information technology (“IT”) and data security;

•	natural disasters, terrorist attacks or similar incidents;

•	existing or future litigation;

•	any changes in the regulatory environments in which we operate, including any increase in restrictions on the ability to operate our networks;

•	any disruption or failure of our third parties’ or key suppliers’ provisioning of products or services;

•	material adverse changes in labor matters, including labor campaigns, negotiations or additional organizing activity, and any resulting financial, operational and/or reputational impact;

•	the ability to make payments on our debt or to repay our existing indebtedness when due;

•	adverse change in the ratings of our debt securities or adverse conditions in the credit markets;

•	changes in accounting assumptions that regulatory agencies, including the Securities and Exchange Commission (“SEC”), may require, which could result in an impact on earnings; and,

•	changes in tax laws, regulations and existing standards and the resolution of disputes with any taxing jurisdictions.

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•	providing customers with affordable rate plans while eliminating annual service contracts;

•	allowing customers easier options to upgrade their eligible devices when they want;

•	reimbursing qualifying customers’ early termination fees and/or remaining phone payments when they switch from other carriers and trade-in their phones;

•	allowing customers to stream music without it counting against their high speed data allotment;

•	providing Wi-Fi calling and texting for customers with capable smartphones;

•	giving qualified customers the ability to roll-over up to 20 GB per year of their unused high-speed data automatically each month;

•	providing reduced United States to international calling rates, and providing messaging and data roaming while traveling abroad at no extra charge;

•	allowing customers to access coverage and calling, as well as 4G LTE data, across the U.S., Mexico and Canada at no extra charge;

•	providing select video streaming services without it counting against their high speed data allotment on qualifying plans;

•	offering eligible new (through December 31, 2016) or existing (as of June 6, 2016) customers ownership in the Company with a free share of T-Mobile stock or an additional share of T-Mobile stock for every new active account each customer refers through December 31, 2016, subject to a maximum of 100 shares in a calendar year;

•	enabling eligible customers who download the T-Mobile Tuesday app to be informed about and to redeem products and services offered by participating business partners each Tuesday;

•	offering eligible customers a full hour of free in-flight Wi-Fi on their smartphone on all Gogo-equipped domestic flights;

•	giving our customers one simple rate plan, T-Mobile ONE™, that includes unlimited calls, unlimited text and unlimited high-speed 4G LTE data on their device; and

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•	beginning in 2017, with our introduction of Un-carrier Next, T-Mobile ONE includes:

•	monthly wireless service fees and taxes in the advertised monthly recurring charge;

•	paying participating customers back for data that is not used in a month if they use less than 2GB high-speed data/month; and

•	giving customers the first-ever price guarantee on an unlimited 4G LTE plan and allowing our customers to keep their T-Mobile ONE price until they decide to change it.

•	Branded postpaid customers generally include customers that are qualified to pay after using wireless communication services;

•	Branded prepaid customers generally include customers who pay for wireless communication services in advance. Our branded prepaid customers include customers of T-Mobile and MetroPCS; and

•	Wholesale customers include Machine-to-Machine (“M2M”) and MVNO that operate on our network, but are managed by wholesale partners.

•	65% branded postpaid customers;

•	31% branded prepaid customers; and

•	4% wholesale customers, roaming and other services.

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Our T-Mobile ONE plan (T-Mobile ONE), which was launched in September 2016 as phase 12.0 of our Un-carrier initiatives. T-Mobile ONE gives our customers unlimited calls, unlimited text and unlimited high-speed 4G LTE data on their device. On T-Mobile ONE, video typically streams at DVD (480p) quality and tethering is at maximum 3G speeds. Customers can choose to add on additional features to T-Mobile ONE for an additional cost. On T-Mobile ONE Plus customers also receive unlimited High Definition Video Day Passes, Voicemail to Text, NameID, unlimited Gogo in-flight internet passes on capable domestic flights and up to two times faster speeds when traveling abroad in 140+ countries and destinations. On T-Mobile ONE Plus International, customers receive the benefits of T-Mobile ONE Plus as well as free and reduced calling from the U.S. to foreign countries and unlimited high-speed 4G LTE mobile hotspot data in the U.S., Mexico and Canada.

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In January 2017, we introduced the latest in our Un-carrier initiatives, Un-carrier Next, where monthly wireless service fees and taxes are included in the advertised monthly recurring charge for T-Mobile ONE. We also unveiled Kickback on T-Mobile ONE, where participating customers who use 2 GB or less of data in a month, will get an up to a $10 credit on their next month’s bill per qualifying line. In addition, we introduced the Un-contract for T-Mobile ONE with the first-ever price guarantee on an unlimited 4G LTE plan, which allows T-Mobile ONE customers to keep their price for service until they decide to change it.

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Simple Choice plans, which were launched in 2013 as part of phase 1.0 of our Un-carrier initiatives, eliminated annual service contracts and simplified the lineup of consumer rate plans to one affordable plan for unlimited voice and messaging services with the option to add data services. On January 25, 2017, we streamlined our Simple Choice plan offerings to new customers into our T-Mobile ONE plan.

•	Depending on their credit profile, qualifying customers who purchase a device from us have the option of financing all or a portion of the purchase price at the time of sale over an installment period of up to 24 months using our Equipment Installment Plan (“EIP”).

•	In addition, qualifying customers who finance their initial device with an EIP can enroll in our JUMP!® program (“JUMP!”) to later upgrade their device. Upon a qualifying JUMP! upgrade, the customer’s remaining EIP balance is settled provided they trade-in their used device at the time of upgrade in good working condition and purchase a new device from us on a new EIP.

•	In 2015, we introduced JUMP! On Demand. With JUMP! On Demand, a low monthly payment covers the cost of leasing a new device and gives qualified customers the freedom to exchange it for a new device up to three times in 12 months for no extra fee. Upon device upgrade or at lease end, customers must return their device in good working condition or purchase their device.

•	We owned or had agreements to own an average of 86 MHz of spectrum across the top 25 markets in the U.S. as of December 31, 2016, comprised of an average of 12 MHz in the 700 MHz band, 30 MHz in the 1900 MHz PCS band and 44 MHz in the AWS band. This is compared to an average of 85 MHz of spectrum across the top 25 markets in the U.S. as of December 31, 2015.

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•	Over the last year, we have entered into and closed on various agreements for the acquisition and exchange of 700 MHz A-Block, AWS and PCS spectrum licenses. See Note 5 – Goodwill, Spectrum Licenses and Other Intangible Assets of the Notes to the Consolidated Financial Statements.

•	In addition, we intend to opportunistically acquire spectrum licenses in private party transactions and future Federal Communications Commissions (“FCC”) spectrum license auctions, including the broadcast incentive auction of low-band 600 MHz spectrum licenses that is currently in-progress.

•	We have continued to build out our network to concentrate our cell sites where our customers need data most. We had approximately 66,000 cell sites, including macro sites and distributed antenna system network nodes as of December 31, 2016, compared to approximately 64,000 cell sites as of December 31, 2015.

•	In 2015, we completed the shutdown of the MetroPCS Code Division Multiple Access (“CDMA”) network. The migration of customers from the MetroPCS CDMA network onto T-Mobile’s LTE and Evolved High Speed Packet Access Plus network provides faster network performance for MetroPCS customers with compatible handsets.

•	We continue to expand our coverage breadth and currently provide 4G LTE coverage to 314 million people, up from zero 4G LTE coverage four years ago. We are targeting to provide 320 million people with 4G LTE coverage by year-end 2017.

•	We own 700 MHz A-Block spectrum covering 272 million people or approximately 84% of the U.S. population. The spectrum covers all of the top 10 market areas and 29 of the top 30 market areas in the U.S.

•	We have deployed our 700 MHz A-Block spectrum in over 500 market areas covering more than 252 million people under the name “Extended Range LTE.” We expect to continue to aggressively roll-out new 700 MHz market areas in 2017 including Chicago, Eastern Montana, and substantially all of the remaining population in 700 MHz licensed areas.

•	At the end of the fourth quarter of 2016, approximately 70% of spectrum was being used for 4G LTE compared to 52% at the end of the fourth quarter of 2015. We expect to continue to re-farm spectrum currently committed to 2G and 3G technologies.

•	Re-farmed spectrum enables us to continue expanding Wideband LTE, which currently covers 232 million people. Wideband LTE refers to markets that have bandwidth of at least 15+15 MHz dedicated to 4G LTE.

•	VoLTE currently comprises approximately 67% of total voice calls compared to 39% in December 2015. Moving voice traffic to VoLTE frees up spectrum and allows for the transition of spectrum currently used for 2G and 3G to 4G LTE. We are leading the U.S. wireless industry in terms of VoLTE migration.

•	Carrier aggregation is live for our customers in 674 cities. This advanced technology delivers superior speed and performance by bonding two or three discrete spectrum channels together.

•	4x4 MIMO is currently available in more than 300 cities. This technology effectively delivers twice the speed, and incremental network capacity, to customers by doubling the number of data paths between the cell site and a customer's device.

•	We have rolled out 256 QAM, which increases the number of bits delivered per transmission to enable faster speed.

•	Innovative programs like Binge On and T-Mobile ONE also create capacity by optimizing video for mobile viewing. These programs deliver material capacity benefits to both customers and our network. Since the launch of Binge On, our customers have watched more than 4 billion hours of optimized video.

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•	human error such as responding to deceptive communications or unintentionally executing malicious code;

•	physical damage, power surges or outages, or equipment failure, including those as a result of severe weather, natural disasters, terrorist attacks, and acts of war;

•	theft of customer and/or proprietary information offered for sale for competitive advantage or corporate extortion;

•	unauthorized access to our IT and business systems or to our network and critical infrastructure and those of our suppliers and other providers;

•	supplier failures or delays; and

•	system failures or outages of our business systems or communications network.

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•	incurring additional indebtedness and issuing preferred stock;

•	paying dividends, redeeming capital stock, or making other restricted payments or investments;

•	selling or buying assets, properties, or licenses, including participating in future FCC auctions of spectrum or private sales of spectrum;

•	developing assets, properties, or licenses that we have or in the future may procure;

•	creating liens on assets;

•	engaging in mergers, acquisitions, business combinations, or other transactions;

•	entering into transactions with affiliates; and

•	placing restrictions on the ability of subsidiaries to pay dividends or make other payments.

•	limiting our flexibility in planning for, or reacting to, changes in our business or the communications industry or pursuing growth opportunities;

•	reducing the amount of cash available for other operational or strategic needs; and

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•	placing us at a competitive disadvantage to competitors who are less leveraged than we are.

•	diversion of management attention from running our existing business;

•	increased costs to integrate the networks, spectrum, technology, personnel, customer base and business practices of the business involved in any such transaction with our business;

•	difficulties in effectively integrating the financial and operational reporting systems of the business involved in any such transaction into (or supplanting such systems with) our financial and operational reporting infrastructure and internal control framework in an effective and timely manner;

•	potential exposure to material liabilities not discovered in the due diligence process or as a result of any litigation arising in connection with any such transaction;

•	significant transaction expenses in connection with any such transaction, whether consummated or not;

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•	risks related to our ability to obtain any required regulatory approvals necessary to consummate any such transaction;

•	acquisition financing may not be available on reasonable terms or at all and any such financing could significantly increase our outstanding indebtedness or otherwise affect our capital structure or credit ratings; and

•	any business, technology, service, or product involved in any such transaction may significantly under-perform relative to our expectations, and we may not achieve the benefits we expect from our transaction, which could, among other things, also result in a write-down of goodwill and other intangible assets associated with such transaction.

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•	increased consumer complaints and potential examinations or enforcement actions by federal and state regulatory agencies, including but not limited to the Consumer Financial Protection Board, the FCC and the FTC;

•	violation of financial services and consumer protections regulations may result in regulatory fines, penalties, enforcement actions, civil litigation, and/or class action lawsuits.

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•	the incurrence of debt (excluding certain permitted debt) if our consolidated ratio of debt to cash flow for the most recently ended four full fiscal quarters for which financial statements are available would exceed 5.25 to 1.0 on a pro forma basis;

•	the acquisition of any business, debt or equity interests, operations or assets of any person for consideration in excess of $1 billion;

•	the sale of any of our or our subsidiaries’ divisions, businesses, operations or equity interests for consideration in excess of $1 billion;

•	any change in the size of our board of directors;

•	the issuances of equity securities in excess of 10% of our outstanding shares or to repurchase debt held by Deutsche Telekom;

•	the repurchase or redemption of equity securities or the declaration of extraordinary or in-kind dividends or distributions other than on a pro rata basis; or

•	the termination or hiring of our chief executive officer.

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•	our or our competitors’ actual or anticipated operating and financial results; introduction of new products and services by us or our competitors or changes in service plans or pricing by us or our competitors;

•	analyst projections, predictions and forecasts, analyst target prices for our securities and changes in, or our failure to meet, securities analysts’ expectations;

•	transaction in our common stock by major investors;

•	Deutsche Telekom’s financial performance, results of operation, or actions implied or taken by Deutsche Telekom;

•	entry of new competitors into our markets or perceptions of increased price competition, including a price war;

•	our performance, including subscriber growth, and our financial and operational metric performance;

•	market perceptions relating to our services, network, handsets, and deployment of our LTE platform and our access to iconic handsets, services, applications, or content;

•	market perceptions of the wireless communications industry and valuation models for us and the industry;

•	conditions or trends in the Internet and the industry sectors we operate in;

•	changes in our credit rating or future prospects;

•	changes in interest rates;

•	changes in our capital structure, including issuance of additional debt or equity to the public;

•	the availability or perceived availability of additional capital in general and our access to such capital;

•	actual or anticipated consolidation, or other strategic mergers or acquisition activities involving us or our competitors, or other participants in related or adjacent industries, or market speculations regarding such activities;

•	disruptions of our operations or service providers or other vendors necessary to our network operations;

•	the general state of the U.S. and world politics and economies, including changes in interest rates; and

•	availability of additional spectrum, whether by the announcement, commencement, bidding and closing of auctions for new spectrum or the acquisition of companies that own spectrum, and the extent to which we or our competitors succeed in acquiring additional spectrum.

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•	any applicable contractual or charter restrictions limiting our ability to pay dividends;

•	our earnings and cash flows;

•	our capital requirements;

•	our future needs for cash;

•	our financial condition; and

•	other factors our board of directors deems relevant.

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•	A narrative explanation from the perspective of management of our financial condition, results of operations, cash flows, liquidity and certain other factors that may affect future results;

•	Context to the financial statements; and

•	Information that allows assessment of the likelihood that past performance is indicative of future performance.

•	In June 2016, we introduced #GetThanked, a history-making move dedicated exclusively to saying “thank you” to our customers. This program, offered to our customers as part of their T-Mobile service: (i) offers eligible new (through December 31, 2016) or existing (as of June 6, 2016) customers ownership in the Company with a free share of T-

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In September 2016, we introduced our T-Mobile ONE plan, a move that gives our customers unlimited calls, unlimited text and unlimited high-speed 4G Long Term Evolution (LTE) data. On T-Mobile ONE, video typically streams at DVD (480p) quality and tethering is at maximum 3G speeds. Customers can choose to add on additional features to T-Mobile ONE for an additional cost. On T-Mobile ONE Plus customers also receive unlimited High Definition Video Day Passes, Voicemail to Text, NameID, unlimited Gogo in-flight internet passes on capable domestic flights and up to two times faster speeds when traveling abroad in 140+ countries and destinations. On T-Mobile ONE Plus International, customers receive the benefits of T-Mobile ONE Plus as well as free and reduced calling from the U.S. to foreign countries and unlimited high-speed 4G LTE mobile hotspot data.

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In January 2017, we introduced, Un-carrier Next, where monthly wireless service fees and all taxes are included in the advertised monthly recurring charge for T-Mobile ONE. We also unveiled Kickback on T-Mobile ONE, where participating customers who use 2 GB or less of data in a month, will get up to a $10 credit on their next month’s bill per qualifying line. In addition, we introduced the Un-contract for T-Mobile ONE with the first-ever price guarantee on an unlimited 4G LTE plan which allows T-Mobile ONE customers to keep their price for service until they decide to change it.

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•	Total revenues increased $5.2 billion, or 16%, to $37.2 billion in 2016 primarily driven by growth in service and equipment revenues as further discussed below. The MVNO Transaction shifted Branded postpaid revenues to Wholesale revenues, but did not materially impact total revenues.

•	Service revenues increased $3.0 billion, or 12%, to $27.8 billion in 2016 primarily due to growth in our average branded customer base as a result of strong customer response to our Un-carrier initiatives and the success of our MetroPCS brand and continued growth in new markets.

•	Equipment revenues increased $2.0 billion, or 30%, to $8.7 billion in 2016 primarily as a result of higher lease revenues, which are recognized over the lease term, resulting from the launch of our JUMP! On Demand program at the end of the second quarter of 2015, an increase in the number of devices sold and a higher average revenue per device sold.

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Operating income increased $1.7 billion, or 84%, to $3.8 billion in 2016 primarily due to higher total revenues as well as increased gains on disposals of spectrum licenses, partially offset by higher depreciation and amortization from an increase in the number of devices leased under our JUMP! On Demand Program, higher costs of equipment sales primarily from an increase in the number of devices sold and a higher average cost per device and higher Selling, general and administrative expenses to support customer growth and retention.

•	Net income increased $727 million, or 99%, to $1.5 billion in 2016 primarily due to higher operating income driven by the factors described above, partially offset by higher interest expense related to higher average debt and higher income tax expense. Additionally, 2016 included $509 million of net, after-tax gains on disposal of spectrum licenses compared to $100 million in 2015.

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Adjusted EBITDA increased $3.0 billion, or 41%, to $10.4 billion in 2016 primarily from higher service revenues and gains on disposal of spectrum licenses, partially offset by increases in selling, general and administrative expenses to support customer growth. Lower losses on equipment in 2016 primarily due to an increase in lease revenues resulting from the launch of our JUMP! On Demand program at the end of the second quarter of 2015. Revenues associated with leased devices are recognized over the lease term.

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Net cash provided by operating activities increased $721 million, or 13%, to $6.1 billion in 2016. The increase was primarily due to an increase in net non-cash income and expenses included in Net income primarily due to changes in Depreciation and Amortization, Deferred income tax expense and Gains on disposal of spectrum licenses expense, as well as an increase in Net income. The increase was partially offset by an increase in net cash outflows from changes in working capital.

•	Free Cash Flow increased $743 million, or 108%, to $1.4 billion in 2016. The increase was primarily from higher net cash provided by operating activities as discussed above. Cash purchases of property and equipment includes capitalized interest of $142 million and $246 million in 2016 and 2015, respectively.

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•	A 13% increase in the number of average branded postpaid phone and mobile broadband customers, driven by strong customer response to our Un-carrier initiatives and promotions for services and devices;

•	Higher device insurance program revenues primarily from customer growth; and

•	Higher regulatory program revenues; partially offset by

•	An increase in the non-cash net revenue deferral for Data Stash; and

•	The impact of reduced Branded postpaid revenues resulting from the MVNO Transaction.

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•	A 13% increase in the number of average branded prepaid customers driven by the success of our MetroPCS brand; and

•	Continued growth in new markets.

•	The impact of the increased Wholesale revenues resulting from the MVNO Transaction;

•	Growth in customers of certain MVNO partners; and

•	An increase in data usage per customer.

•	An increase of $1.2 billion in lease revenues resulting from the launch of our JUMP! On Demand program at the end of the second quarter of 2015. Revenues associated with leased devices are recognized over the lease term.

•	An increase of $570 million in device sales revenues, primarily due to a 9% increase in the number of devices sold. Device sales revenue is recognized at the time of sale.

•	Higher revenue from revenue share agreements with third parties; and

•	An increase in co-location rental income from leasing space on wireless communication towers to third parties.

•	Cost of services consists primarily of costs directly attributable to providing wireless service through the operation of our network, including direct switch and cell site costs, such as rent, network access and transport costs, utilities, maintenance, associated labor costs, long distance costs, regulatory program costs, roaming fees paid to other carriers and data content costs.

•	Cost of equipment sales consists primarily of costs of devices and accessories sold to customers and dealers, device costs to fulfill insurance and warranty claims, costs related to returned and purchased leased devices, write-downs of inventory related to shrinkage and obsolescence, and shipping and handling costs.

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Selling, general and administrative consists of costs not directly attributable to providing wireless service for the operation of sales, customer care and corporate activities. These include commissions paid to dealers and retail employees for activations and upgrades, labor and facilities costs associated with retail sales force and administrative space, marketing and promotional costs, customer support and billing, bad debt expense, losses from sales of receivables and back office administrative support activities.

•	Higher regulatory program costs and expenses associated with network expansion and the build-out of our network to utilize our 700 MHz A-Block spectrum licenses, including higher employee-related costs; partially offset by

•	Lower long distance and toll costs; and

•	Synergies realized from the decommissioning of the MetroPCS CDMA network.

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•	A 9% increase in the number of devices sold; and

•	An increase in the impact from returned and purchased leased devices.

•	Employee-related costs;

•	Commissions driven by an increase in branded customer additions; and

•	Promotional costs.

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$1.5 billion in depreciation expense related to devices leased under our JUMP! On Demand program launched at the end of the second quarter of 2015. Under our JUMP! On Demand program, the cost of a leased wireless device is depreciated over the lease term to its estimated residual value. The total number of devices under lease was higher year-over-year, resulting in higher depreciation expense; and

•	The continued build-out of our 4G LTE network.

•	Operating income, the components of which are discussed above, increased $1.7 billion or 84% and

•	Interest expense to affiliates decreased $99 million or 24% primarily from:

•	Changes in the fair value of embedded derivative instruments associated with our Senior Reset Notes issued to Deutsch Telekom in 2015; partially offset by

•	Higher interest rates on certain Senior Reset Notes issued to Deutsch Telekom, which were adjusted at reset dates in the second quarter of 2016 and in 2015. Partially offset by:

•	Income tax expense increased $622 million or 254% primarily from:

•	Higher income before income taxes; and

•	A higher effective tax rate. The effective tax rate was 37.3% in 2016, compared to 25.1% in 2015. The increase in the effective income tax rate was primarily due to income tax benefits for discrete income tax items recognized in 2015 that did not impact 2016; partially offset by the recognition of $58 million of excess

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•	Interest expense increased $333 million or 31% primarily from:

•	Higher average debt balances with third parties; and

•	Lower capitalized interest costs of $83 million primarily due to a higher level of build out of our network to utilize our 700 MHz A-Block spectrum licenses in 2015, compared to 2016.

•	Interest income decreased $159 million or 38% primarily due to $166 million lower imputed interest income associated with devices financed through EIP resulting from:

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An increase in sales of certain EIP receivables pursuant to our EIP receivables sales arrangement resulting from an increase in the maximum funding commitment in June 2016. Interest associated with EIP receivables is imputed at the time of a device sale and then recognized over the financed installment term. See Note 2 – Equipment Installment Plan Receivables of the Notes to the Consolidated Financial Statements; and

•	Focus on devices financed on JUMP! On Demand in the third and fourth quarters of 2015 following the launch of the program of at the end of the second quarter 2015.

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•	Growth in the number of average branded postpaid and mobile broadband customers, driven by strong customer response to our Un-carrier initiatives and promotions for services and devices;

•	Increased customer adoption of upgrade and insurance programs; and

•	Increased regulatory program revenues; partially offset by

•	Lower branded postpaid phone ARPU.

•	Growth in the number of average branded prepaid customers driven by the success of our MetroPCS brand promotional activities; and

•	Continued growth in expansion markets.

•	Revised agreements with certain MVNO partners in 2015; partially offset by

•	Growth in customers of certain MVNO partners.

•	Lower international roaming revenues driven by changes in contractual arrangements with certain roaming partners; and

•	A reduction in early termination fees.

•	Lower average revenue per device sold, due in part to the impact of customers shifting to leasing higher-end devices under our JUMP! On Demand program; partially offset by

•	Growth in the number of devices and accessories sold.

•	Synergies realized from the decommissioning of the MetroPCS CDMA network;

•	Lower lease expense associated with spectrum license lease agreements; and

•	A reduction in certain regulatory program costs; partially offset by

•	Increases related to our network expansion and build-out of our 700 MHz A-Block spectrum.

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•	Lower average cost per device sold, mainly due to the impact of customers shifting to leasing higher-end devices with JUMP! On Demand; partially offset by

•	Growth in the number of devices and accessories sold.

•	Employee-related costs;

•	Promotional costs;

•	Commissions; and

•	Bad debt expense and losses from sales of receivables primarily resulting from growth in the customer base and in the EIP program.

•	$163 million in 2015 which primarily consisted of a non-cash gain of $139 million from spectrum license transactions with Verizon recorded in the fourth quarter of 2015; as compared to

•	$840 million in 2014 which primarily consisted of non-cash gains from spectrum license transactions with Verizon, and to a lesser extent, a non-cash gain from a spectrum license transaction with AT&T during the fourth quarter of 2014.

•	Operating income, the components of which are discussed above, increased $649 million or 46% and

•	Interest income increased $61 million or 17% primarily attributable to higher interest income from devices financed through EIP. Interest associated with EIP receivables is imputed at the time of sale and then recognized over the financed installment term. Partially offset by:

•	Interest expense to affiliates increased $133 million or 48% primarily from:

•	Changes in the fair value of embedded derivative instruments associated with the Senior Reset Notes issued     to Deutsche Telekom; partially offset by

•	Lower capitalized interest costs associated with the build out of our network to utilize our 700 MHz A-Block     spectrum licenses.

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•	Income tax expense increased $79 million or 48% primarily from:

•	Higher income before income taxes; partially offset by

•	A lower effective tax rate. The effective tax rate was 25.1% in 2015, compared to 40.2% in 2014. The     decrease in the effective income tax rate was primarily due to the impact of discrete income tax items     recognized in 2015, including changes in state and local income tax laws and the recognition of foreign tax credits.

•	Interest expense increased $12 million or 1% primarily from:

•	Higher debt balances with third parties; partially offset by

•	Lower capitalized interest costs associated with the build out of our network to utilize our 700 MHz     A-Block spectrum licenses.

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•	Higher branded prepaid net customer additions primarily due to the success of our MetroPCS brand, continued growth in new markets and distribution expansion, partially offset by an increase in the number of qualified branded prepaid customers migrating to branded postpaid plans; partially offset by

•	Lower branded postpaid mobile broadband net customer additions primarily due to higher deactivations resulting from churn on a growing branded postpaid mobile broadband customer base, partially offset by higher gross customer additions; and

•	Lower branded postpaid phone net customer additions primarily due to lower gross customer additions from higher deactivations on a growing customer base, partially offset by lower churn as well as an increase in the number of qualified branded prepaid customers migrating to branded postpaid plans as well as the optimization of our third-party distribution channels.

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Lower branded postpaid phone net customer additions primarily due to lower gross customer additions in 2015, compared to 2014, which included the introduction of Un-carrier 4.0 Contract Freedom and certain attractive family rate plan promotions, partially offset by approximately 765,000 qualified branded prepaid customers upgrading to branded postpaid plans in 2015, compared to approximately 420,000 in 2014; partially offset by

•	Higher branded postpaid mobile broadband net customer additions primarily due to higher gross customer additions driven by promotions for mobile broadband devices, partially offset by higher deactivations resulting from the discontinuation of certain promotional pricing for mobile broadband services and ongoing competitive activity in the marketplace; and

•	Higher branded prepaid net customer additions primarily due to higher gross customer additions driven by the success of our MetroPCS brand promotional activities and continued growth in new markets, partially offset by approximately 765,000 qualified branded prepaid customers upgrading to branded postpaid plans in 2015, compared to approximately 420,000 in 2014.

•	The MVNO Transaction as the customers transferred had a higher rate of churn; and

•	Increased customer satisfaction and loyalty from ongoing improvements to network quality, customer service and the overall value of our offerings in the marketplace.

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•	A decrease in certain customers, which have a higher rate of branded prepaid churn;

•	Strong performance of the MetroPCS brand; and

•	A methodology change in the third quarter of 2015 as discussed below.

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•	Decreases due to an increase in the non-cash net revenue deferral for Data Stash;

•	Dilution from promotional activities; partially offset by

•	Higher data attach rates;

•	The positive impact from our T-Mobile ONE rate plans;

•	The transfer of customers as part of the MVNO transaction as those customers had lower ARPU;

•	Continued growth of our insurance programs; and

•	Higher regulatory program revenues.

•	Dilution from the continued growth of customers on Simple Choice plans and promotions targeting families; partially offset by

•	An increase in regulatory program revenues.

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