explicitly set the caller ID number in originate

Otherwise, starting in asterisk 11.13.0, if you have the following
caller ID:

   "#25"

then asterisk believes that this caller ID is composed of:

   name: NULL
   location: #25

This has an impact on the SIP INVITE that asterisk sends, and some
phones (Aastra) will reject this SIP INVITE.

Said differently, starting from asterisk 11.13.0, you couldn't call #25
from the dialer xlet.