I found this strange behavior from my Polycom phones lately.
I have configured the following chord-set for ring-back tone.
It worked fine with "voIpProt.SIP.musicOnHold.uri" configured.
I removed MOH setting and made a call to the phone.
Then I could not hear any call progress tone although the phone was ringing.
And the progress tone got back when I restored MOH.
This was observed in SPIP 335 with USC 4.0.1B and SPIP 650 with USC 4.0.3F phones.
Any idea to resolve it will be appreciated.
that parameter has absolutely nothing to do with call progress.
From the UCS 4.0.1 Admin Guide page 538:
A URI that provides the media stream to play for the remote party on hold. This parameter is used if reg.x.musicOnHold.uri is Null.
There is an issue with the tones at present since UCS 3.3.2 (from memory) up until the current UCS 4.x.x if the sound starts with a tone instead of a break.
Have a look at this search results => here <= and work with your Polycom reseller if further support is needed.
Thanks for the info and I'll look into it.
I know it is strange but really I could turn progressing tone on and off as I set MOH uri.