From the server side

[boatman]

Here is a text version of the SDP packet sent by your SJPhone.

Message Header
Via: SIP/2.0/UDP 98.232.161.137:5051;branch=z9hG4bK-b3129c99;rport=5051
From: boatman <sip:17473672943@proxy01.sipphone.com>;tag=a6ec789 5cba2c8d9o1
To: "jdstroy" <sip:798554@voxalot.com>;tag=5259192c598a
Contact: <sip:798554@129.252.103.250:5060;natp2us1=yes>
Call-ID: b8335045-1daa54e9@192.168.100.12
CSeq: 101 INVITE
Content-Length: 268
Content-Type: application/sdp
Record-Route: <sip:64.34.173.199;lr=on;ftag=a6ec7895cba2c8d9o1>, <sip:72.51.47.59;lr=on;ftag=a6ec7895cba2c8d9o1>
Server: SJphone/1.65.377a (SJ Labs)
Supported: replaces,norefersub,timer


Message Body
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): - 3441413139 3441413139 IN IP4 192.168.200.1
Session Name (s): SJphone
Connection Information (c): IN IP4 192.168.200.1
Time Description, active time (t): 0 0
Media Description, name and address (m): audio 49076 RTP/AVP 0 101
Connection Information (c): IN IP4 64.34.173.199
Media Attribute (a): rtpmap:0 PCMU/8000
Media Attribute (a): rtpmap:101 telephone-event/8000
Media Attribute (a): fmtp:101 0-16
Media Attribute (a): setup:active
Media Attribute (a): sendrecv
Media Attribute (a): nortpproxy:yes


In the Message Body, is that second Connection Information line inserted by Voxalot or is your SJPhone doing that? What does nortpproxy mean?

I am not familiar with SJPhone, but setting Full Address of Record to 798554@us.voxalot.com may help. Watch the SDP packet sent by SJPhone at beginning of call. The idea is to create SIP packets which give Voxalot's IP addresses, not your public IP address or your LAN IP address.

In your Voxalot account, when you set Symmetric NAT Handling to 'Yes', and also use "Optimize Audio Path", it seems to me that Voxalot should be processing the SDP packet in order to remove all instances of non-Voxalot IP addresses. Does that make sense to you?

[jdstroy]

Hi Boatman,

I haven't really gotten around to poking at SJPhone on Voxalot recently. I presume this is from the Wireshark dump from last time, correct?

Originally Posted by boatman

is that second Connection Information line inserted by Voxalot or is your SJPhone doing that?

I highly suspect it's my UA, SJPhone. I don't think Voxalot knows what my internal IP address is.

Originally Posted by boatman

What does nortpproxy mean?

Your guess is as good as mine. Given that SJLabs is pretty much dead, I can only speculate that nortpproxy indicates that SJPhone doesn't want to use an RTP proxy. How I can change this option, I'd love to know. But that applies to Phoner, PhonerLite, and everything else, too -- where's the Hope/Change button? Seriously, I need a Change Advanced Settings button somewhere.

Originally Posted by boatman

I am not familiar with SJPhone, but setting Full Address of Record to 798554@us.voxalot.com may help.

I found another option, too, which supposedly corrects the Contact URI to the Full Address of Record. I've set this, but I haven't had many calls to test it.

Originally Posted by boatman

In your Voxalot account, when you set Symmetric NAT Handling to 'Yes', and also use "Optimize Audio Path"

Symmetric NAT Handling is set to yes, but Optimize Audio Path doesn't exist. (I'm not using Voxalot with any other providers, you see.)

Originally Posted by boatman

it seems to me that Voxalot should be processing the SDP packet in order to remove all instances of non-Voxalot IP addresses. Does that make sense to you?

Sure. That makes sense to me; that's what FreeWorldDialup did when I registered against their outbound proxies. They filtered all the call setup information and forwarded RTP data to/from my UA.

[boatman]

Yes, that's the session description protocol (SDP) packet from when I called you a while back.

I was thinking of your internal IP address as the first Connection Information line, as it comes earlier in the packet than the other Connection Information line.

That must be it, nortpproxy = "no rtp proxy".

Maybe SJPhone has some obscure text configuration files somewhere on your disk. Maybe you can use a text search tool and look for things like "nortpproxy".

[jdstroy]

Hi Boatman,

Originally Posted by boatman

I was thinking of your internal IP address as the first Connection Information line, as it comes earlier in the packet than the other Connection Information line.

You are right. I misread what you wrote. The other IP address, I'm not sure what puts it into the SDP packet, but it's a Voxalot IP address.

Originally Posted by boatman

That must be it, nortpproxy = "no rtp proxy".

Maybe SJPhone has some obscure text configuration files somewhere on your disk. Maybe you can use a text search tool and look for things like "nortpproxy".

No dice. SJPhone uses the registry (no keys or values with "RTP proxy" or "rtpproxy" in them) and a set of binary files.

I'm just about ready to give up on using SJPhone on Voxalot, since it's no longer actively maintained, but it still works on Jeff Pulver's network, FWD. Additionally, I haven't really found a UA that works well enough with Voxalot at my location/configuration.

[boatman]

Martin,

Now that you have returned, please tell us more about how Voxalot modifies SIP packets when Symmetric NAT Handling is set to 'Yes'.

It looks as if Voxalot is failing to fully replace the "Connection Information" line, as I expect it should, when Symmetric NAT Handling is set to 'Yes'. The result is two "Connection Information" lines which may confuse some user agents, hence the problem reported here by jdstroy.

[jdstroy]

I'm bumping this in hopes of finding out what's up. Unfortunately, it looks like FreeWorldDialup finally kicked the bucket, so now I have a good reason to care that Voxalot works as stated, heheh.

Have there been any revelations on why the RTP proxy doesn't always work? The setup that I'm using isn't too rare, I should think... IPKall <=> Voxalot <=> My SIP UA

Summary of previous posts: The streams between my SIP UA and Voxalot are handled through a SNAT and a CNAT -- that's why the RTP proxy matters. My UAs are Xlite and SJphone, but I'm willing to try most other SIP clients. I have SNAT Handling enabled.

[boatman]

Originally Posted by jdstroy

Have there been any revelations on why the RTP proxy doesn't always work?

Yes, I have just revealed the secret in this post. I suggest you try proxy01.us1.voxalot.com and let me know how it goes.