NEC SL2100 SIP Trunk RTP Media Ports

[Tinos]

Hi all.
I have come across documents that say UDP RTP ports 10020-10531 must be forwarded on the Firewall to the IP address in 84-26. Other mention ports 10020-10083.
1. Which one is correct?
2. Can the port range be reduced to 10020-10028 if I have 8 channels?

 

[daddybadger]

Source 10000-60000 to Destination 10020-10277

UDP 10000 - 60000

UDP 10020 - 10277

If you reduce the port range you will have issues with audio.

 

[Tinos]

Please add some notes to your response. I am failing to follow.

 

[daddybadger]

So you would forward the source RTP ports from your itsp and the destination would be 10020-10277 on the sl IPLB or rather the DSP address you have assigned in 10-12-09. If you have 8 sip trunks you don't reduce the RTP ports because the voice packets could fall anywhere within that port range. Any ports that are not forwarded will be dropped which will cause 1 way audio.

 

[CoralTech]

1020-10083 UDP forwarded to the media gateway IP of your Sl2100.

 

[Tinos]

To conclude please clarify which ports goes were using the below codes:
No VOIPDB card installed.
10-12-01 IP Address = 0.0.0.0
10-12-09 VOIP IP Address = 192.168.1.2
84-26-01 VOIPDB DSP IP Address = 192.168.1.3
Port 5060 forward to 192.168.1.2
Ports 10020-10083 forward to 192.168.1.3
Is the above correct?

 

[CoralTech]

Yes for SIP trunks.

 

[meyer1y2k]

Each conversation requires (2) UDP ports per active conversation. They are paired so Convo #1 uses 10020 AND 10021 for the 2 audio paths (tx/rx). Convo 2 would use 10022 and 10023. My understanding is they are dynamically allocated so when a conversation ends, those 2 ports are assigned to the next active convo. For 16 (sorry meant 8) IP channels 10020-10035 should suffice (8*2 being 16). I would probably just open up to 10049 because NEC sometimes does weird things, but that is just me.

You can see this if you put a WireShark on the VoIP card and just observe on the LAN. Then extend it out to the router. It is an interesting process to observe.

 

[CoralTech]

You are overthinking it. Just open that range so you never have to touch it again if you expand. These ports ALSO are used for sip phones as well.