NAT problems with voice

What is the complete current contents of rtp.conf and is there any logging at startup to indicate a problem with it?

Ok,tnx this one is solved.
There was no context described in rtp.conf, added [general], this problem is gone.

Now I have another one. While im trying to establish a call through dongle, i can hear rings, but when abonent answers, dongle goes down.

raspbxCLI> dongle show device state dongle0
-------------- Status -------------
Device : dongle0
State : Free
Audio : /dev/ttyUSB2
Data : /dev/ttyUSB1
Voice : Yes
SMS : Yes
Manufacturer :
Model :
Firmware : E171
IMEI :
IMSI : 863
**78
GSM Registration Status : Registered, home network
RSSI : 17, -79 dBm
Mode : No Service
Submode : No service
Provider Name : Beeline
Location area code : "FDC3"
Cell ID : "51C3"
Subscriber Number : Unknown
SMS Service Center : 002B003700390030003
Use UCS-2 encoding : Yes
USSD use 7 bit encoding : No
USSD use UCS-2 decoding : Yes
Tasks in queue : 0
Commands in queue : 0
Call Waiting : Disabled
Current device state : start
Desired device state : start
When change state : now
Calls/Channels : 0
Active : 0
Held : 0
Dialing : 0
Alerting : 0
Incoming : 0
Waiting : 0
Releasing : 0
Initializing : 0

log—

[2016-11-22 01:14:22] ERROR[1195] chan_dongle.c: [dongle0] timedout while waiting ‘OK’ in response to ‘AT’
[2016-11-22 01:14:22] VERBOSE[1195] chan_dongle.c: – [dongle0] Dongle has disconnected
[2016-11-22 01:14:22] VERBOSE[1329][C-0000002e] app_dial.c: == Everyone is busy/congested at this time (1:0/0/1)
[2016-11-22 01:14:22] VERBOSE[1329][C-0000002e] pbx.c: – Auto fallthrough, channel ‘SIP/Denas-00000003’ status is ‘CHANU
NAVAIL’
[2016-11-22 01:14:22] WARNING[1329][C-0000002e] channel.c: Prodding channel ‘SIP/Denas-00000003’ failed
[2016-11-22 01:14:22] VERBOSE[1329][C-0000002e] pbx.c: – Executing [h@default:1] Hangup(“SIP/Denas-00000003”, “”) in new stack
[2016-11-22 01:14:22] VERBOSE[1329][C-0000002e] pbx.c: == Spawn extension (default, h, 1) exited non-zero on ‘SIP/Denas-00000003’
[
[2016-11-22 01:14:49] VERBOSE[495] chan_dongle.c: – [dongle0] IMEI 863115010306878 IMSI 250991435667032 found on data_tty=/dev/ttyUSB1 audio_tty=/dev/ttyUSB2
[2016-11-22 01:14:49] VERBOSE[495] chan_dongle.c: – [dongle0] Trying to connect on /dev/ttyUSB1…
[2016-11-22 01:14:49] VERBOSE[495] chan_dongle.c: – [dongle0] Dongle has connected, initializing…
[2016-11-22 01:14:49] VERBOSE[1376] at_response.c: – [dongle0] Dongle initialized and ready

I found that it could be 1)problem with power, btw im using 2.5A power supply, ive reeded,that i shoud be enough. And before it was possible to establish a call.

  1. problem with network signal.(17, -79 dBm is enough or not?)

Coud it be some another source of problem to check? Place a usb hub now is a bit difficult, because im far from raspberry.

Hello.
Im back)
My previous problem resolved with use of AT command
AT^SYSCFG=13,0,3FFFFFFF,0,3

Now i have new one to ask.
When im calling to echo with client behind NAT, its not always working, i found the difference in log (in bad cases, at ast_rtcp_read he dont use new destination to send packets).
While im calling from the same client to the GSM number, all fine. After a delay for ~15 seconds voice appears.

Sent RTP packet to 172.28.162.136:5062 (type 00, seq 035159, ts 107360, len 000160)
Sent RTP packet to 172.28.162.136:5062 (type 00, seq 035160, ts 107520, len 000160)
Sent RTP packet to 172.28.162.136:5062 (type 00, seq 035161, ts 107680, len 000160)
[2017-01-23 21:46:40] DEBUG[6777][C-00000016]: res_rtp_asterisk.c:3893 ast_rtcp_read: RTCP NAT: Got RTCP from other end. Now sending to address 185.13.203.106:16871
Sent RTP packet to 172.28.162.136:5062 (type 00, seq 035162, ts 107840, len 000160)
Sent RTP packet to 172.28.162.136:5062 (type 00, seq 035163, ts 108000, len 000160)

The point is that i cant call from outside of the nat to internal clients. Call establishes,but without voice.
Do you have any ideas?