I am only running the new software on two sites currently (neither have modems). I plan on moving all 10 to 9.0 UR2 soon. If I was you I would use another solution such as a SIP ATA of some sort. MUCH cheaper than the Mitel solution and they only affect the devices you choose. I wish that I would have gone this route on this site but Mitel basically gave us the equipment after some ADIs (they wanted someone to try it for they we think).
Good luck.
