[Asterisk-Users] call transfer to external phone number

[Giuseppe]

Hi!
Is it possible to transfer a call to an external phone instead of
transferring the call to internal phone?
(I'm sorry for my bad english, I hope you understand)
When, during a call, I digit "#123", the call is transferred to internal 
extension "123",
but if I digit "#external_phone_number", it tells me that it's impossible.
Any idea?

Thanks a lot!

Giuseppe