Sometimes, when a call is answered, the person answering will hear like a system reorder tone,and cannot hear person on the other end. Person on the other end will not hear the tone, but can hear person who answered their call. This will sometimes happen initially,or after the call is transferred. Seems to be only on incoming calls.

What kind of trunking? I have seen digital circuits do this both card and carrier. Also, run a diag for errors to make sure that your 4GC or SVC is not having problems. SOMETIMES this can be a time slot issue and this is why after you xfer it it clears up and goes onto the next time slot.