Property and Equipment (Tables)

The components of property and equipment, excluding amounts transferred to held for sale, were as follows:


(in millions)	Useful Lives	December 31, 2024		December 31, 2023

Land		$	69	$	72
Buildings and equipment	Up to 30 years	4,377		4,465
Wireless communications systems	Up to 20 years	65,778		65,628
Leasehold improvements	Up to 10 years	2,588		2,489
Capitalized software	Up to 8 years	18,566		22,573
Leased wireless devices	Up to 16 months	145		400
Construction in progress	N/A	3,377		3,286
Accumulated depreciation and amortization		(56,367)		(58,481)

Property and equipment, net		$	38,533	$	40,432

Activity in our asset retirement obligations was as follows:


(in millions)	Year Ended December 31, 2024		Year Ended December 31, 2023

Asset retirement obligations, beginning of year	$	1,716	$	1,852

Liabilities incurred	21		28
Liabilities settled	(307)		(399)
Accretion expense	69		71
Changes in estimated cash flows	36		164


Asset retirement obligations, end of period	$	1,535	$	1,716

Classified on the consolidated balance sheets as:

Other current liabilities	$	109	$	133
Other long-term liabilities	1,426		1,583