We are investigating a problem where callers to customer VOIP numbers and not getting any ring tones, calls are going through but no 'ringing' tones are being generated. This is being investigated by our engineers now.
We have managed to reproduce the problem, which is the first step to finding the cause and fixing it. Sorry for any inconvenience this may be causing. There has also been some disruption to calls in to our offices today as a result of our investigations.
We believe we have got to the bottom of this issue, and should be rolling out an update later today.
Call servers will upgrade at some point this evening with the necessary fix for the lack of ring tone. Thank you for your patience.