Greetings, I have a CCM 4.2 with a MGCP controlled gateway terminating an ISDN PRI. When I make a call to an external PSTN user, the call sounds fine. When I then initiate an adhoc conference call to include a second PSTN user, the two external parties claim that they can barely hear each other (soft voice). As the IP phone user, I can still hear each party and they can both hear me.
The problem does not occur when all of the parties are IP phones or if just one of the parties is an external PSTN user. The problem only appears when there are two external PSTN users.
Thanks in advance.