24advance billings and customer deposits

As at (millions)	June 30, 2018		December 31, 2017		January 1, 2017
			(adjusted – Note 2(c))		(Note 2(c))
Advance billings	$	517	$	506	$	456
Deferred customer activation and connection fees	11		13		17
Customer deposits	15		21		15
Regulatory deferral accounts	1		1		8

Contract liabilities	544		541		496
Other	75		91		88

	$	619	$	632	$	584

Incremental accounting policy disclosure due to initial application of IFRS 15 (see Note 2)

Contract liabilities

Advance billings are recorded when billing occurs prior to provision of the associated service; such advance billings are recognized as revenue in the period in which the services and/or equipment are provided. Similarly, and as appropriate, upfront customer activation and connection fees are deferred and recognized over the average expected term of the customer relationship.

Contract liabilities represent our future performance obligations to customers in respect of services and/or equipment and for which we have received the consideration from the customer or for which the amount is due from the customer. Our contract liability balances, and the changes in those balances, are set out in the following table:

		Three-month periods ended June 30						Six-month periods ended June 30						Year ended December 31,
(millions)	Note	2018			2017			2018			2017			2017
Balance, beginning of period		$	788		$	777		$	780		$	732		$	732
Revenue deferred in previous period and recognized in current period		(637		)	(626		)	(689		)	(670		)	(670		)
Net additions arising from operations		628			633			686			723			718
Regulatory deferral account drawdown		—			(1		)	—			(3		)	(7		)
Additions arising from business combinations		1			5			3			6			7

Balance, end of period		$	780		$	788		$	780		$	788		$	780

Current								$	691		$	700		$	691
Non-current	27
Deferred revenues								72			67			71
Deferred customer activation and connection fees								17			21			18

								$	780		$	788		$	780

Reconciliation of contract liabilities presented in the consolidated statements of financial position — current
Gross contract liabilities								$	691		$	700		$	691
Reclassification to contract assets for contracts with contract liabilities less than contract assets								(142		)	(143		)	(146		)
Reclassification from contract assets for contracts with contract assets less than contract liabilities								(5		)	(5		)	(4		)

								$	544		$	552		$	541