The carrying amounts of external-use software development costs as of December 31, 2023 and 2022 were as follows:


	December 31,
	2023		2022

	(In thousands)
Gross carrying amount	$	239,038	$	225,004
Accumulated amortization	(172,379)		(144,244)
External-use software development costs, net (1)	$	66,659	$	80,760

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(1) Included in other long-term assets in the Consolidated Balance Sheets.

The Company recorded $28.7 million, $29.0 million, and $26.4 million to cost of revenues for amortization of external-use software development costs for the years ended December 31, 2023, 2022, and 2021, respectively.

The estimated future amortization expenses for external-use software development costs were as follows:


	December 31, 2023

	(In thousands)
2024	$	25,354
2025	18,331
2026	12,792
2027	6,837
2028	2,980
Thereafter	365
Total	$	66,659