Configuration is SPA9000 + SPA400 + SPA942's, all with latest firmware.
I initially was using just the SPA400 (line 1) for external calls (3 pots lines). Music on hold worked fine (put a call, either inbound or outbound, on hold using the SPA942 hold button, external caller hears SPA9000 MOH - soothing guitar music).
I then added an ITSP (Nexvortex) on line 2.
When a call comes inbound via the ITSP, can put the caller on hold and they hear MOH.
However, on outbound calls over the ITSP, when a caller is put on hold, they hear nothing. Then when you press the line key to pick up the held call, the remote end hears a tiny snippet of the MOH before being connected back to the station that picked up the call.
Now here's the interesting thing. When I use the call park feature instead of the hold button, there is no problem. External caller can always hear the SPA9000 MOH.
Any ideas? We need the MOH to work on both directions when using the hold button (our users do not use and do not want to use the park feature).
Thanks for your help!