Завелось. Всем спасибо
same=>n(ks-6121), NoOp()
same=>n, Dial(PJSIP/${EXTEN}@sipprov-endpoint,,Ttb(dial_create_chan,s,1)))
[dial_create_chan]
exten => s,1,Set(PJSIP_HEADER(add,P-Asserted-Identity)=<sip:564455@3.3.3.3\;transport=udp>)
same => n,Return()