Asterisk AMI and Atxfer

I am using AMI with Atxfer to transfer calls
It works well from which I transfer to interiors but if I want to transfer the call to an external thing does not go through …

Place an Example of what I send to AMI:

Working example “transfer to an internal”:
$ in = “Action: Atxfer \ r \ n”;
$ in. = “Channel: SIP / 10-000000bf \ r \ n”;

     $ in. = "Exten: 12 \ r \ n";
     $ in. = "Context: default \ r \ n";
     $ in. = "Priority: 1 \ r \ n \ r \ n";

Example that does not work “transfer to a cell”:
$ in = “Action: Atxfer \ r \ n”;
$ in. = “Channel: SIP / 10-000000bf \ r \ n”;

     $ in. = "Exten: 3349472 .... \ r \ n";
     $ in. = "Context: default \ r \ n";
     $ in. = "Priority: 1 \ r \ n \ r \ n";

I hope you can help me

Thank you

I think I’ve already solved alone …

I do not have to use the context when I call a piece of furniture or an external number

do confirm with later examples

I thought you are like just do not put the Context: