Problem with outbound calls being disconnected when a cell phone voicemail answers the call

I am having a problem with one location that has Aastra 9480i’s. When people in this office use their SIP phone to call a cell phone, it will ring and if the cell phone voicemail answers, then it either hangs up the call or plays a ringback to the sip phone.
I have registered another aastra phone at a different location and on the same phone system. This phone does not have any problems calling cell phones and leaving messages at all…
Any help with this issue would be greatly appreciated.

Firmware of the Aastra 9480i’s are all
Is this possibly a firmware issue on the phone?