IP-telephony: it is impossible to get through to the mobile subscriber - connection reset, what should I do?

Question

Telephony

Hello!
We work on the following link:
Zoiper at employees -> CoMagic -> WestCall (ip-telephony) - we dial some numbers, the connection is interrupted (no beeps, nothing, hang up immediately)
480 Temporarily Unavailable.

We call some numbers, for example, to other countries - without problems. On some mobile phones it is not possible. For example, I just can't get through to myself.

The program for dialing was changed - both Zoiper on phones and PhonerLite on Windows.
CoMagic was removed from the chain , they called directly through Westcall ip-telephony.
New accounts created - does not work.

Westcall says carriers are blocking us, we have a direct city phone in Moscow, the services are legal, we are on the list of Roskomnadzor as a personal data operator, we have not been involved in flooding.
Megafon, for example, claims that there are no blacklists, only if the users themselves have not blocked us.
At the same time - I remind you - I can not get through to my personal mobile number, where there are definitely no black lists. It's just a disconnect.

Westcall suggests that we change our phone number. Advise what to do? What other information to get?

The screenshot shows when the problem started.

Answer 1

thanks to the operators
for diagnostics, change the number and catch the second peak,
then the third ,
then how in the feces centers you will have a pool of numbers

Answer 2

tcpdump call can you collect between the PBX and the VoIP provider?

Answer 3

Communication problems are always solved by the outgoing side. Contact Westcall, only they can trace the call beyond themselves, especially if the call leaves them, then everything is OK on your side. And if not OK, then Westcall should say so.

Answer 4

Today all of a sudden it worked. We are trying to understand the reason.

Answer 5

If an operator substitutes a number from the capacity of another operator as a caller ID, it will be blocked. Not all, but many, especially large ones.