Changes in property and equipment account for the years ended December 31, 2019 and 2018 are as follows:

	Cable and wire facilities			Central office equipment			Cellular facilities			Buildings and improvements			Vehicles, aircraft, furniture and other network equipment			Information origination and termination equipment			Land and land improvements			Property under construction			Total
	(in million pesos)
As at December 31, 2017
Cost		207,220			119,642			209,504			27,076			58,964			17,595			3,458			50,585			694,044
Accumulated depreciation, impairment and amortization		(159,765	)		(101,680	)		(159,323	)		(18,022	)		(51,083	)		(13,473	)		(267	)		(3,524	)		(507,137	)
Net book value		47,455			17,962			50,181			9,054			7,881			4,122			3,191			47,061			186,907
Year ended December 31, 2018
Net book value at beginning of the year		47,455			17,962			50,181			9,054			7,881			4,122			3,191			47,061			186,907
Additions (Note 4)		1,278			565			758			120			1,158			2,107			—			52,504			58,490
Disposals/Retirements		(10	)		(27	)		(60	)		(140	)		(95	)		—			—			(9	)		(341	)
Reclassifications (Note 14)		19			(1	)		—			127			(23	)		—			1,117			—			1,239
Transfers and others		10,409			8,237			37,881			265			1,465			1,176			—			(59,433	)		—
Translation differences charged directly to cumulative translation adjustments		—			3			—			1			(3	)		—			—			—			1
Deconsolidation of a subsidiary		—			—			(65	)		(794	)		(273	)		—			—			—			(1,132	)
Impairment losses recognized during the year (Note 5)		(299	)		(292	)		(858	)		(480	)		(29	)		—			—			—			(1,958	)
Depreciation of revaluation increment on investment properties transferred to property and equipment charged to other comprehensive income		—			—			—			(2	)		—			—			—			—			(2	)
Depreciation and amortization		(11,381	)		(10,480	)		(17,499	)		(2,162	)		(3,382	)		(2,334	)		(2	)		—			(47,240	)
Net book value at end of the year		47,471			15,967			70,338			5,989			6,699			5,071			4,306			40,123			195,964
As at December 31, 2018
Cost		217,773			128,321			217,164			26,546			58,711			20,823			4,576			40,123			714,037
Accumulated depreciation, impairment and amortization		(170,302	)		(112,354	)		(146,826	)		(20,557	)		(52,012	)		(15,752	)		(270	)		—			(518,073	)
Net book value		47,471			15,967			70,338			5,989			6,699			5,071			4,306			40,123			195,964
Year ended December 31, 2019
Net book value at beginning of the year		47,471			15,967			70,338			5,989			6,699			5,071			4,306			40,123			195,964
Effect of adoption of IFRS 16 (Note 2)		—			—			(244	)		(1	)		—			—			—			—			(245	)
Net book value at the beginning of the year (as restated)		47,471			15,967			70,094			5,988			6,699			5,071			4,306			40,123			195,719
Additions (Note 4)		1,448			856			557			176			3,804			2,987			3			63,040			72,871
Disposals/Retirements		(24	)		—			(99	)		(3	)		(109	)		—			—			(77	)		(312	)
Reclassifications (Note 14)		12			(8	)		(762	)		(82	)		15			1			—			(30	)		(854	)
Transfers and others		10,374			7,720			32,290			541			1,247			4,696			21			(56,889	)		—
Translation differences charged directly to cumulative translation adjustments		(1	)		(1	)		—			(4	)		2			—			—			—			(4	)
Adjustments		—			—			—			(20	)		—			—			—			—			(20	)
Depreciation of revaluation increment on investment properties transferred to property and equipment charged to other comprehensive income		—			—			—			(3	)		—			—			—			—			(3	)
Depreciation and amortization (Note 3)		(8,084	)		(3,857	)		(17,025	)		(1,102	)		(3,410	)		(1,782	)		(3	)		—			(35,263	)
Net book value at end of the year		51,196			20,677			85,055			5,491			8,248			10,973			4,327			46,167			232,134
As at December 31, 2019
Cost		192,535			135,340			220,238			26,762			62,097			28,224			4,597			46,167			715,960
Accumulated depreciation, impairment and amortization		(141,339	)		(114,663	)		(135,183	)		(21,271	)		(53,849	)		(17,251	)		(270	)		—			(483,826	)
Net book value		51,196			20,677			85,055			5,491			8,248			10,973			4,327			46,167			232,134

Interest capitalized to property and equipment that qualified as borrowing costs amounted to Php1,455 million, Php1,524 million and Php816 million for the years ended December 31, 2019, 2018 and 2017, respectively. See Note 5 – Income and Expenses – Financing Costs – Net. The average interest capitalization rate used was approximately 5% for each of the years ended December 31, 2019, 2018 and 2017.

Our net foreign exchange differences, which qualified as borrowing costs, amounted to nil, Php411 million and Php106 million for the years ended December 31, 2019, 2018 and 2017, respectively.

The cost of fully depreciated property and equipment that are still being used in the Group’s operations amounted to Php149,119 million and Php171,867 million as at December 31, 2019 and 2018, respectively.

As at December 31, 2019 and 2018, the estimated useful lives of our property and equipment are estimated as follows:

In December 2017, Smart and DMPI recognized an impairment loss of Php3,913 million pertaining to network improvement project involving spectrum refarm and long-term evolution rollout. These assets include Radio Access Network, or RAN, equipment such as base transceiver sets, base station controllers, access radios, antennas, radio network controllers, power and related support facilities, among others, including software licenses and implementation services affecting the Quezon City and Marikina areas.

In 2018, Digitel and DMPI recognized an impairment loss amounting to Php1,096 million and Php862 million, respectively, as a result of the full migration of fixed line subscribers to PLDT network for Digitel and continued network convergence strategy for DMPI.

See Note 3 – Management’s Use of Accounting Judgments, Estimates and Assumptions – Impairment of non-financial assets and Estimating useful lives of Property and equipment.

On January 28, 2020, PLDT was authorized by the Board of Directors to negotiate and enter into a contract for the sale of Smart Towers Property. The transaction is deemed subject to the confirmation of the Philippine Competition Comisssion, or PCC, on Non-Coverage.