Letter in Prefix / Dial pattern

I just got my mobile operator to connect my phone directly as an SIP Mobile Extension. This makes all my calls go through Asterisk directly.

I have one big problem thought. When the incoming call is coming to my my asterisk it is formated with a capital letter “C” in the prefix. The operator calls this a C-Prefix and it is made like this by purpose. Initially my plan was to match the prefix directly to remove it like this: _C12345|[0.] but the FreePBX GUI does not allow me to use an letter.

I guess this is by purpose since it isn’t normal to send letters in a phone number. Whenever I try to match it and save i get the following message: “Dial pattern is invalid”.

I have tried the following as prefix:

The first and second give me an error and the third does not match the prefix. Please help.

Setup: Asterisk 11.3.0 / FreePBX setup.

There is a context in extensions.conf


that would be easy to modify for your situation (basically replace + with C) , add the modified context to extensions_custo.conf

and send your inbound calls there.

Okey. Perfect! Then it is only one problem. I cant seem to localize my configuration files. I thought and understand from other posts that they should be under /etc/asterisk or /dev/bin/asterisk, but I am not able to find them. I run my setup on a RasPBX. I have searched all over and can not seem to find it. Especially the extensions_* files.

use find /-name exten*, but all my RasPBX’ have a /etc/asterisk directory.

So, I found the configs.
I have now tried everything and it does not prepend anything no mather what i try. Could someone maybe help me create the exten line to match my numbers?

I want to call with my trunk named “siptrunk”. When i call with my cell, the incoming number shown is the number i call. So if I call 0285526 it will show as C123450285526. So the C12345 have to be omited in some way. And after the match it should be sent to my trunk called siptrunk. It could also be sent to from-internal if that makes it easier.

Sorry, i said wrong! not prepend, but ommit the C12345. It should not be shown or used on the incoming / outgoing call.