3. Contracts with Customers

Revenue from contracts by customer channel and by major product line is summarized as follows (dollars in thousands):


	Three Months Ended
	March 31,
	2018		2017
Business
Data services	$	14,846	$	15,617
Voice services		19,652		21,258
Hosted and managed services		1,599		1,532
Equipment and related services		3,029		5,443
		39,126		43,850
Consumer
Video services		11,225		10,594
Internet services		7,105		6,681
Voice services		15,272		16,986
		33,602		34,261
Wholesale carrier data		13,932		12,828
Other		2,562		3,571
	$	89,222	$	94,510

The majority of revenue from all channels and product lines, except for equipment and related services, is recognized over time as the data, voice or video service is made available to the customer. The majority of revenue from equipment and related services is recognized at a point in time as the equipment is delivered or when installation is complete. Installation may occur in phases. We recognize revenue of an individual phase when completed if it represents a stand-alone component that can operate independent of other components.

Contract Balances

Receivables consisted of the following (dollars in thousands):


	March 31,		December 31,
	2018		2017
Customers and other	$	27,930	$	36,118
Allowance for doubtful accounts		(3,811)		(3,889)
	$	24,119	$	32,229

Contract liabilities consisted of the following (dollars in thousands):


	March 31,		December 31,
	2018		2017
Current presented as advance billings	$	9,349	$	14,807
Noncurrent deferred revenue included in other liabilities		28,554		28,036
	$	37,903	$	42,843

Revenue recognized in the period that was included in the contract liability balances at the beginning of the period amounted to $2.8 million for the three months ended March 31, 2018.

Performance Obligations

The Company generally delivers telecommunication services ratably over the contract term. The majority of services are invoiced in advance and balances are due within 30 days of issuance of an invoice or statement to the customer. Many customers are on a month-to-month contract that can be cancelled at any time or within short notice. Even for those customers on long term contracts, the Company will generally invoice the customer based on services provided during the month either at the beginning or end of the monthly service period. For business equipment and related services, the Company will generally invoice upon delivery or project completion. Certain large projects with installation periods of up to one year may be invoiced at set milestones. Invoices are also due within 30 days of issuance.

Certain IRU contracts for extended periods of up to 25 years are invoiced at the beginning of the contract term. The revenue from such contracts is recognized over time as services are provided over the contract term. The expected revenue to be recognized is as follows (dollars in thousands):


Year ended December 31,
2018 (remaining months)	$	2,015
2019		2,686
2020		2,686
2021		2,686
2022		2,686
Thereafter		30,112
	$	42,871

Costs to Obtain Contracts

Costs to obtain contracts representing sales commissions on certain products have been deferred and recognized over the expected contract term. Total costs deferred amounted to $7.2 million at March 31, 2018. Costs amortized to expense amounted to $0.7 million for the three months ended March 31, 2018.