Q.Sig Path Replacement between Asterisk and Ericsson

Try to setting up E1 connection between Asterisk and Ericsson MD110, the connection was OK using Q.Sig but requirement to call transfer back and forth between 2 systems without holding E1 channel if both caller and calling are on the same system. This feature is called "Path Replacement" or "Route Optimization". Seems this possible by setting as following:

Asterisk:

1. use latest version of libpri 

2. set DAHDI (or zaptel) signaling to 'qsig' or 'pri_cpe'

3. set 2 parameters in zapata.conf

facilityenable=yes

transfer=yes

4. use Transfer command to transfer the call back to Ericsson

Ericsson:

1. enable "Route Optimization" by using command

ASPAC:PARNUM=66,PARVAL=1  // enable route optimization

ASPAC:PARNUM=66,PARVAL=0 // disable route optimization

At the time of this post, no actual test has been done. I will update the test result if this setting is actually work.

I found 2 references that good for reading:

http://bugs.digium.com/view.php?id=7778

http://readlist.com/lists/lists.digium.com/asterisk-users/12/61194.html