Asterisk periodic unilateral hearing on some numbers?

Question

Asterisk

Friends help, do not kick much, the topic is hackneyed. I read the book, I know about the paid support. But I can't afford it yet and I'm asking for your help.
Set up Asterisk 13 on CentOS 7. There are two interfaces 1) local with Internet access 192.168.7.x 2) dedicated vlan provider with sip telephony 10.12.20.xxx. routes are written. iptables is disabled.
There is a problem when calling to the same provider, there are no other problems. When we recruit to the city, we hear the client, but he does not hear us. But sometimes it happens that he still hears us. Nat in the asterisk is disabled for me, but I tried to enable it, it did not help. The provider says the traffic is visible in both directions. Tell me where to dig. I took a dump if it helps I post it.
I tried to replace the asterisk with a sip phone, there are no problems, everything works. So venyu Asterisk, tried FreePBX did not help. Asterisk is configured on an ESXi server on CentOS. Before ESXI from the provider is configured by a trunk through several tsisok.

https://drive.google.com/open?id=1aVw-6Gf15s_Kkou0...
https://drive.google.com/open?id=1hxjYEQNGusKdlvsr...

Answer 1

1. Show output grep 'extern\|localn' /etc/asterisk/sip*.conf
2. Show routes netstat -rn
3. Show

asterisk -rx 'sip show peers' | grep IP_ОПЕРАТОРА_СВЯЗИ

4. Do you have internal subscribers in this local area network?
5. Show the settings of the peer -your carrier.