Grandstream. Forwarding works, but displays the number they are calling?

Question

VoIP

I have a Grandstream UCM6202. Internal numbers have been created there, and
many of these numbers also use their own sip lines for calls to
landlines and mobiles.
I set up forwarding on these internal numbers in functions ->
presence status under what conditions the forwarding is triggered, the call
timeout (the time after which the call is redirected), I indicated what would be
redirected if not answered, let's say to the mobile external number of the
person who owns this internal number. And
forwarding works, BUT the mobile number of the person who
owns this internal number and sip-line, the station calls this sip
-line. That is, as if he is dialing himself from a softphone to
mobile. As a result, people do not see who is calling them when
call forwarding is triggered, because
their sip line number is displayed on their mobile phone. Well, I think you understand. tell me how to fix this
? Help me please.
Thank you in advance for your reply!

Answer 1

You will not get such pleasure, at least if your telephone operator is not fierce outcasts.
Roughly speaking: you are not allowed to call from your sip lines, substituting someone else's number as CallerID - because this is a form of number substitution, which allows you to carry out all sorts of unpleasant exploits.