Incoming Attended Transfer


I have a TE410p installed on Power Edge 2850 server. It works with Zaptel 1.4.6, Libpri 1.4.2 and Asterisk 1.4.13.



I am using Grandstream GXP-2000

I have this problem:

1- I received an incoming call from zaptel in LINE1.

2- I changed to the next line (LINE2), automatically the incoming call (LINE1) is on hold.

3- I call to a particular extension, sip extension. The extension answers the call and then I inform to the person that I will transfer a call to him.

4- I go back to the line with the incoming call LINE 1, I tell the person I will transfer him immediately, press the TRNF button followed by the LINE2 button BUT nothing happens.

5- The LINE2 stays in on hold but there is no way to return to that line and I keep the communication with LINE1.

I can transfer the call if I never return to LINE1, pressing the TRNF button from LINE2 followed by LINE1 button. That works perfect so BLIND TRANSFER but I am not sure what is the problem in the other case.

Any suggestions!