RTP not get thru if user was via internet

[sisob]

Hello,

I have problem with direct rtp with OXE Rel 10.x. Currently, my customer have OXE 10.x with all users are SIP extensions. They installed 3CX and Bria/X-lite softphone at Android phones. Internal calls has no problem. But when user connected via internet then having problem. The call is connected/established but no audio both direction. I use wireshark to trace the rtp. I found that the rtp from internal user will go directly to external. It's no possible since the port forwarding only allowed the rtp from external network (internet) flow to OXE internal IP@.
So how to solve this kind of problem? To disable direct rtp?

[cavagnaro]

Use a SBC...
SIP is NOT NAT friendly unless you have a special router to do so

[sisob]

Hi Cavagnaro,

Router is using for internet connection. Using Mikrotik router. What special router you mean?

Tks.

[cavagnaro]

One that supports NAT for SIP.

[sisob]

The router aleeady support NAT. But evertime call made from internal to mobile user on internet, the RTP always go directly to internet IP. That's doesn't allowed. Supposed the RTP goes to OXE. This is what i am facing.

[cavagnaro]

Again. Read slowly. SIP IS NOT NAT Friendly.
You need a SBC or put it directly on Internet. Search on the Internet more details or get an expert to guide you properly.



Sent from my XPeria Z

[vad]

About problem with NAT.

F.e. you PBX address 10.253.253.1, VoIP address 10.253.253.5 (private).
For external calls you use real address 192.X.X.X and NAT translation.

From outside you can call your PBX - 192.X.X.X --> (NAT) 10.253.253.1.
But PBX will send to external caller - for RTP flow you need to use 10.253.253.5 (!!!). This is internal private address. You cannot send RTP packets to this address.

So you have 2 way:
- use SBC
- use VoIP board (INTIP, GA) with real Internet address (not from private address)

[sisob]

Hi Vad,

My IP configuration as follow :
- OXE 10.10.10.10
- Public IP 182.16.252.155

The IP setting on Softclient (3CX) on Android, Local PBX IP 10.10.10.10, External PABX IP 182.16.252.155.
I don't install GA. Only GD. Is that caused teh problem?

Tks.

[vad]

For SIP calls - you will send messages to 182.16.252.155 (this step is Ok, NAT works and OXE receive messages on address 10.10.10.10)
But PBX will send to your Softclientsend RTP port address 10.10.10.10 and your Softclient will send RTP packets (voice) to 10.10.10.10 (not to 182.16.252.155).

[sisob]

Hi Vad,

You correct that the Softclient should send RTP packets to 10.10.10.10, but i used Wireshark the RTP (internal) goes to 182.16.252.155 (direct RTP). But the router configures open port for RTP to goes to external users thru 10.10.10.10. This is the problem that no RTP at both side. Any idea how to make the RTP from softclient goes to OXE IP@ at 10.10.0.10? (Non-direct RTP).
I was tried using Asterisk SIP PABX and it's work fine. Because the RTP goes to Asterisk SIP Server and from SIP Server to 182.16.252.155 (not direct RTP).

Tks.