Request : Need help assistance : cannot send T.38 , DCS DSR

I have fax KX-FT982 connected to AddPack ap100. Using voip provider sip.mtt.ru at Saint-Petersburg. My Internet connection have no external static IP.
Using simple NAT rules, now gw is oracle linux 6.4
{

iptables -L -v -n

Chain INPUT (policy ACCEPT 1165K packets, 2950M bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
3959 784K ACCEPT all – eth1 * 0.0.0.0/0 0.0.0.0/0
3070 634K ACCEPT all – * eth1 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT 965K packets, 2519M bytes)
pkts bytes target prot opt in out source destination

iptables -L -v -n -t nat

Chain PREROUTING (policy ACCEPT 10030 packets, 1195K bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 8354 packets, 1088K bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 3886 packets, 276K bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 15 packets, 900 bytes)
pkts bytes target prot opt in out source destination
5066 356K MASQUERADE all – * eth0 0.0.0.0/0 0.0.0.0/0
}

When i setting up ap100 with sip.nnt.ru SIP account (without asterisk), i can send T.38 faxes.
When i setting up ap100 with internal asterisk server, and asterisk set to use sip.mtt.ru trunk, i cannot send T.38 faxes.
Here wireshark picture from mtt.ru provider dump piccy.info/view3/4612947/a098960 … d1bfcd040/

We can see, problem can be in “DCS DSR” signaling, i don`t know how to deal with it.
Same error with asterisk 1.8, 10.2, 11.3.0 (currently i use 11.3.0). OS now is FreeBSD 9.1. I was test asterisk 10.2 at OpenBSD 5.3, same error.
Regarding NAT: i was test gw with pf firewall on OpenBSD, same error.
GW using yota.ru device to access to LTE 4G Internet.

In my asterisk i have that error:
WARNING[100526][C-00000000]: res_rtp_asterisk.c:3468 ast_rtp_read: RTP Read too short

with canreinvite=no in configs i have same error.

VoIP provider don`t know how to solve that probles, so i asking it here.
Thanks in advance.

asterisk log file “messages” pastebin.com/WQug1bMS
asterisk log file “full” pastebin.com/HXQhzsAz

sip.conf pastebin.com/gw1UJGRq
users.conf pastebin.com/37QjJJZr
extensions.conf pastebin.com/8JpKhppn