Polycom SIP firmware version 3.1.0 is due around the end of August. We knew it was coming as Pingtel said they were testing an engineering release, we just didn't know when... and now we do!
The big news for this firmware is Polycom finally supporting the Music on Hold (MoH) standard that sipX utilizes (the Dale Worley IETF Draft)
This will be a huge boost for users of the system!
At present the Snom phones are one of the few who support MoH on sipX.
Here's the sipX MoH page: MoH Page