External redirection problem on inbound calls

Hi All,
I have a problem in call transfer.
I have a DID number and SIP trunk. Inbound and Ounbound calls are working without any problem. I have a dialplan that redirect calls to an external number (my cell phone)that begin with 6 (_6*). When call is made from an internal number (for ex 8000) the call is redirected to my cell phone without any problem.
When the same transfer is made for an external incoming call (first call is sent to an internal number and after 5 seconds it is redirected) the call is dropped. In SIP logs I only see a REFER message and a BYE message going from asterisk. I am suspicious call is dropped because both legs are on the same trunk.
I found some patches but these are not for my relase ( I am not sure if loding these patches would be helpful. Can you please comment on this?

The patches are shown below: