Dial an outside phone as an extension

Dial an outside phone as an extension

How to dial an outside number as an extension with Asterisk?

Dialplan Entry:

exten => 2222,1,AGI(agi://127.0.0.1:4577/call_log)
exten => 2222,2,Set(CALLERID(num)=390xxxxxxxxxx)
exten => 2222,3,Dial(SIP/39028xxxxxxx@voipuser)
exten => 2222,4,Hangup