We’re having an issue currently.
One of the ring groups has nested ring groups (i.e. 100 rings 101 (ext), 102# (ring group), 103# (ring group)), this is set up to hunt which mostly works fine.
When we ring the ring group, we get a ringing tone for the first 10 seconds, after which the hunt goes on to 102# ring group and rings the appropriate extensions, however at this point we have no ring tone on the phones, as such some callers end up hanging up as they believe the call has been disconnected.
This happens when calling in from external numbers or internally.