The following is a description of the principal activities from which we generate our revenue by reportable segment.

Network Solutions includes hardware products and software-defined next-generation virtualized solutions used in service provider or business networks, as well as prior generation products. The majority of the revenue from this segment is from hardware sales. In certain transactions, we are also the lessor in sales-type lease arrangements for network equipment. These arrangements typically include network equipment, network implementation services and maintenance services. Network implementation services and maintenance services are included in the Services & Support segment discussed below. See Note 12 for additional information.

To complement our Network Solutions segment, we offer a complete portfolio of maintenance, network implementation, solutions integration and managed services, which include hosted cloud services and subscription services.

In addition to our reporting segments, we also report revenue in the following three categories – Access & Aggregation, Subscriber Solutions & Experience and Traditional & Other Products.

The following table disaggregates our revenue by reportable segment and revenue category for the three months ended September 30, 2019 and 2018:

	Three Months Ended
	September 30, 2019						September 30, 2018
(In thousands)	Network Solutions		Services & Support		Total		Network Solutions		Services & Support		Total
Access & Aggregation	$	48,902	$	16,212	$	65,114	$	76,046	$	15,855	$	91,901
Subscriber Solutions & Experience⁽¹⁾		40,382		2,094		42,476		37,313		1,239		38,552
Traditional & Other Products		4,734		1,768		6,502		7,684		2,198		9,882
Total	$	94,018	$	20,074	$	114,092	$	121,043	$	19,292	$	140,335

The following table disaggregates our revenue by reportable segment and revenue category for the nine months ended September 30, 2019 and 2018:

	Nine Months Ended
	September 30, 2019						September 30, 2018
(In thousands)	Network Solutions		Services & Support		Total		Network Solutions		Services & Support		Total
Access & Aggregation	$	230,837	$	43,476	$	274,313	$	220,653	$	37,670	$	258,323
Subscriber Solutions & Experience⁽¹⁾		113,545		6,186		119,731		99,396		3,817		103,213
Traditional & Other Products		14,625		5,605		20,230		21,310		6,343		27,653
Total	$	359,007	$	55,267	$	414,274	$	341,359	$	47,830	$	389,189

Revenue is measured based on the consideration we expect to receive in exchange for transferring goods or providing services to a customer and as performance obligations under the terms of the contract are satisfied. For transactions where there are multiple performance obligations, we account for individual products and services separately if they are distinct (if a product or service is separately identifiable from other items and if a customer can benefit from it on its own or with other resources that are readily available to the customer). As of September 30, 2019, we did not have any significant performance obligations related to customer contracts that had an original expected duration of one year or more, other than maintenance services, which are satisfied over time.

The following table provides information about receivables, contract assets and unearned revenue from contracts with customers:

(In thousands)	September 30, 2019		December 31, 2018
Accounts receivable, net	$	90,647	$	99,385
Contract assets⁽¹⁾	$	2,434	$	3,766
Unearned revenue	$	14,022	$	17,940
Non-current unearned revenue	$	4,581	$	5,296

Of the outstanding unearned revenue balance at December 31, 2018, $1.2 million and $11.7 million was recognized as revenue during the three and nine months ended September 30, 2019, respectively.