I've opened a support ticket for this (and I'm waiting to hear back), but thought I'd bring it up here also...
On the OBi110, the RTP KeepAliveInterval is not applied in the case of silence suppression. If silence suppression is enabled for a codec, and there is an extended period of silence, then a RTP packet should be sent to keep the channel alive if KeepAliveInterval is enabled. Otherwise, the ITSP may disconnect the call since no RTP packets have been received. [An obvious workaround is to disable silence suppression, but since silence suppression works fine otherwise, it would be nice to have this fixed.]