4135 IP Phone not allowing 2nd call until "time out"

[nmayfiel]

I have seen some other posts alluding to the same problem that I am having, but can not find if there is a resolution. On the 4135 the first inbound call goes great. If a second call comes in very shortly after the first one is hung up the caller will hear ringing, but the 4135 itself if not ringing. Motortraces indicate the PCX thinks the phone is busy. If you wait awhile it will "time out" and the calls will again work. I would appreciate any help or suggestions anyone could provide. Thank you

[MrAnMo]

How did you program your 4135? It has to be programmed as a sip device.