Iax trunk passing callerid

I have a asterisk 1.4 box connected via a iax trunk to a asterisk 1.2 box.

Im trying to pass callerid info between the boxes.

asterisk 1.4
exten => 3,1,Set(CALLERID(name)=Call for IT Support via IAX)
exten => 3,2,Dial(IAX2/asteriska/88@office/${CALLERID(name)})

On the console I can see it dialing asteriska/88@office/Call for IT Support via IAX

but on the gxp2000 phone on the other end its shows UNKNOWN as the callerid.

exten => 88,1,Dial(SIP/100,30)

Any ideas how I can pass the callerID over the iax link.