I am running asterisk with an IAX2 trunk and SIP extensions.
I am unable to transfer calls using #ext when the call is initiated internally. If we receive a call then the # will work
We have a mixture of clients including x-lite and netcomm v85 phones.
With the netcomm phones we are able to use the phone transfer button successfully.
you need to add a ‘T’ to your Dial options. if you are running TrixBox or A@H then it’s a bit trickier, and you’ll need to work your way through the extensions.conf files looking for Dial statements ? although i understand that outbound dial options are catered for in later builds of A@H or FreePBX.
if you’re using a home-built dialplan then you’ll know where to look.