2. Accounts Receivable

The Company’s accounts receivable are primarily due from resellers and distributors of its video communications products and services. Credit is extended based on evaluation of each customer’s financial condition and, generally, collateral is not required except for certain international customers. Accounts receivable are generally due within 30 days and are stated net of an allowance for doubtful accounts. Accounts that are outstanding longer than contractual payment terms are considered past due. The Company records an allowance on a specific basis by considering a number of factors, including the length of time trade accounts are past due, the Company’s previous loss history, the credit-worthiness of individual customers, economic conditions affecting specific customer industries and economic conditions in general. The Company writes off accounts receivable when they become uncollectible and payments subsequently received on such receivables are credited against write-offs in the period the payment is received.

Changes in the Company’s allowance for doubtful accounts for the three and six months ended June 30, 2012 and 2013 are as follows:

	For the three months ended June 30,							For the six months ended June 30,
	2012				2013			2012				2013
	(Unaudited)				(Unaudited)			(Unaudited)				(Unaudited)
Beginning balance	$	28,135		$		50,998	$		22,292		$		39,018
Bad debt expense		(5,783	)			8,051			5,968				20,031
Uncollectible accounts written off		—				—			(5,908	)			—
Ending balance	$	22,352		$		59,049	$		22,352		$		59,049