Transfer outgoing calls


My Asterisk server seems to be working perfectly the only problem is when I make outgoing calls I can’t seem to transfer calls. I’m sure it’s just a small argument or something somewhere but I can’t seem to find it online. Transferring incoming calls works perfectly.
Does anybody have any ideas?


How are you connecting the lines to Asterisk? How are you trying to do the transfers?

In particular, there are two main ways of doing SIP transfers (native and features.conf ways) and phones typically have one of two ways of handling native attended transfers.

I’m not sure what you mean by how do they connect to Asterisk. The phones are outside of Asterisks LAN and connecting through the external IP of the datacenter where Asterisk is held.
I am doing transfers with the features.conf. The transfer button on the handset itself doesn’t seem to work (I’m using Yealink T20Ps).

OK we’ve eliminated dahdi. IAX, H.323, SIP, skinny, etc?

Ah I see, it’s SIP.

SIP transfer or features transfer? Blind or attended? If SIP blind, does the phone actually do it as an attended transfer?

Features transfer. Both blind and attended. I can’t get the transfers to work at all with outbound calls.

Do you have both T and t options on the Dial application call?

What is dtmfmode set to?

I only have t. To add T do I literally just make it ,tT ?
dtmfmode = rfc2833

I made it tT and it all works perfectly now!
Thank you so much for the help and quick replies.