[asterisk-users] Extensions of sip trunk

[Hans-Peter Jansen]

Hi,

I just started with setting up a new asterisk system, that will operate on a 
sip trunk, but I wonder, how to transfer the calls to different extensions, 
because all calls appear as being send to the base number of the trunk.

E.g. given the trunk range of 1234567800-12345678099, a call to 1234567800 is 
matched by the same pattern as a call to 12345678099.

; matches 12345678099, too
exten => _1234567800,1,Dial(SIP/int)

Except from SIP invite with tcpdump:

INVITE sip:123456780000 at provider:5060 SIP/2.0
From: <sip:013579246800 at provider>;tag=as6bc7cbbc
To: <sip:1234567800099 at other:5060>

I wonder, if I really need to grab the extension with 
Set(DN=${SIP_HEADER(TO):5}) or something similar?

Another issue is, that I don't like asterisk to decline foreign INVITE 
requests. Any best practices from within asterisk on how to ignore SIP 
invitations, that don't match certain criteria (neither local nor from sip 
provider)?

System: openSUSE 42.2, Asterisk 14.5.0

Thanks in advance,
Pete