Goodwill, which relates to our acquisitions of Bluesocket, Inc. and SmartRG, were $7.1 million at December 31, 2018 and $3.5 million at December 31, 2017 of which $6.7 million and $0.4 million is allocated to our Network Solutions and Services & Support reportable segments, respectively, for the year ended December 31, 2018 and of which $3.1 million and $0.4 million is allocated to our Network Solutions and Services & Support reportable segments, respectively, for the year ended December 31, 2017.

We evaluate the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that would more likely than not reduce the fair value of the reporting unit below its carrying amount. We have elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step impairment test. If we determine that it is more likely than not that its fair value is less than its carrying amount, then the two-step impairment test is performed. Based on the results of our qualitative assessment in 2018, we concluded that it was not necessary to perform the two-step impairment test. There were no impairment losses on goodwill recognized for the years ended December 31, 2018, 2017 and 2016.

The following table presents our intangible assets as of December 31, 2018 and 2017:

	2018							2017
(In thousands)	Gross Value		Accumulated Amortization			Net Value		Gross Value		Accumulated Amortization			Net Value
Customer relationships	$	22,455	$	(5,380	)	$	17,075	$	7,474	$	(4,283	)	$	3,191
Developed technology		12,801		(4,867	)		7,934		5,524		(4,663	)		861
Licensed technology		5,900		(520	)		5,380		—		—			—
Supplier relationships		2,800		(1,108	)		1,692		—		—			—
Patents		500		(157	)		343		500		(89	)		411
Licensing agreements		560		(5	)		555		—		—			—
Intellectual property		930		(930	)		—		930		(852	)		78
Non-compete		200		(200	)		—		200		(115	)		85
Trade names		310		(106	)		204		100		(65	)		35
Total	$	46,456	$	(13,273	)	$	33,183	$	14,728	$	(10,067	)	$	4,661

Amortization expense was $2.3 million, $2.9 million and $2.5 million for the years ended December 31, 2018, 2017 and 2016, respectively.

As of December 31, 2018, the estimated future amortization expense of intangible assets is as follows: