Our company has a NEC sv8100 system it has been operating good for the past six years. We use the mobile extension feature extensively. We recently changed providers for our PRI from Logix Communications to AT&T. Before the change the desk phone would ring once then both be desk phone and the mobile extension would ring. Since the changeover in the PRI the desk phone now rings Twice and stops ringing and the call is forwarded to the mobile extension. Voicemails cannot be left on the NEC phone system since the call is not redirected back to the phone system. Any ideas?