Hi, I've managed to setup 2 different VoIP providers through the PBX, both with incoming calls routed to the same extension. However when I put somebody on hold, for 1 of the VoIP provider, music on hold is working. However for the other VoIP provider, music on hold is not working. Putting callers on hold and transfering calls between extensions seems to work for incoming calls through bouth VoIP provider. What are some of the things I can do to troubleshoot and find out where the problem is? Thanks.