Over the last month or so we have received a number of support requests where a prepay VoIP Express account has maintained a call in progress lock even though the last call made had hung up. This has meant that the end user has not been able to make a new call until the call lock is removed.
Despite extensive investigation and attempts to replicate the issue we have not been able to ascertain the cause. So today we have instigated a scheduled procedure to clean up any call locks where there is no corresponding call for the account. If any VoIP Express account is in future affected by this issue the maximum amount of time the account will be locked for is 60 seconds.
We will continue to monitor the situation and look to stop the issue happening in the first place. We estimate that this issue has affected 0.012% of calls made during November 2010.