Obitalk service protocol and VoIP without SIP

[Toulousaing]

Hi guys,

Hope you all doin' well (it's been long time I didn't post).

let me explain you my latest problem.
Let's assume that I have an Obi end that is located in a random country that blocks SIP ports and most importantly SIP protocol (by sniffing packets I guess).
SIP did never work for me over there (as well google voice service).
BUT obitalk service works! NB: I guess that even Obitalk service can be blocked by blocking the right IP adress.
So my first question is:

Question1 : Which protocol is used by Obitalk service?

But this brings me to a more general question:

Question 2 : Is there any way to directly call an end device without signaling protocol whatsoever (SIP, to name it)? Through direct call, knowing IP/ports of the end device.

Many thanks!

[Ostracus]

Not sure, but a RonR post implied ObiTalk is basically for setup between devices, and the Obi's after that communicate directly (the media part). You could naturally try a VPN if blocking is a problem.

[ianobi]

Q1. - I've sniffed OBiTALK calls using Wireshark. They don't show up as voip calls and no SIP protocol is evident. All I see is UDP data being swapped between the devices. I guess it's their own bespoke protocol. It may be SIP that's been encoded somehow.

Q2. - Direct ip to ip calling is possible, but a little tricky to set up. Even when set up you would still need a signalling protocol of some sort. "A" has to tell "B" that it's calling, "B" has to tell "A" that it has answered etc.

Using direct ip calling you can decide yourself which ports are used, so you can avoid the usual 5060, 5061 etc. If the SIP protocol is being used to stop calls, then that's harder to get around.

[Toulousaing]

Hi Ostracus,

Ok I think we agree on the principle, i.e. Obitalk acts like a SIP server to give (at least) the IP of the other end.
But then how is initiated the communication between the two devices? An equivalent of SIP protocol? Or no protocol is involved (i.e. directly RTP with UDP packets sent/received)?

I'm really interested because I'd like to know if Obi (or any other ATA/IP phone) can do the same with SP1/SP2.
A related question is: how does direct call through SIP URI works? No SIP protocol visible in sent/received packets?

VPN is of course a solution, but it involves some drawbacks, most notably the required extra bandwith (due to location of Obi end) and the set-up of home VPN routers (because they could block common VPN providers,...).

Any suggestion is more than welcome, I guess middle eastern users have some experience on this

Cheers

EDIT: ianobi posted while I was posting (see above)

[Toulousaing]

Thanks ianobi,

To sum up your post, there is no way around if SIP protocol itself is being blocked?  

Is there any way to use Obitalk service without connecting to Obitalk servers (that's obviously the weak point if ISP wants to block them)?

Toulousaing

[ianobi]

To sum up your post, there is no way around if SIP protocol itself is being blocked?

I'm not an expert on protocols. SIP is common, but there are others. For example, Google Voice uses XMPP. IAX is another and H.323. H.323 is rarely used now as far as I know.

Is there any way to use Obitalk service without connecting to Obitalk servers (that's obviously the weak point if ISP wants to block them)?

Not as far as I know.

[Ostracus]

Well a VPN doesn't require a "provider". It can be between two routers, one set as a client, the other as a server.

One can also use EoIP routing as well although I'm not certain about the security aspect.

For those who don't know EoIP is basically bridging two LANs together over a WAN connection. One could pretend two or more Obidevices are on the same LAN.

I believe RonR already has an example of two Obidevices connecting directly to each other over a LAN.

[Toulousaing]

Well a VPN doesn't require a "provider". It can be between two routers, one set as a client, the other as a server.

Yes I mentioned above about VPN home routers as a solution because I don't want to use VPN providers. And VPN home routers means extra complexity (set-up, +1 VPN router for each Obi end) and more importantly extra bandwith (some of my Obi ends have low bandwith internet access).

I have strong requirements: "low-bandwith-compatibility", and "censorship-proofness".
And "soft" requirements: low complexity (using only Obi ends/any other ATA/IP phone would be good), and stability over time.

Concerning EoIP solution, I guess that I can't avoid the set up of a router behind each Obi end.
But what is the overall required bandwith using codecs like G729 (which has low required bandwith)?
If this is comparable to that of VPN, then I guess it is not worth investing in that solution.

NB1: I'm not asking to help me to breach any law, as some ISP do it without any supporting law, i.e. THEY are on illegal side.

NB2: I don't really care about security. And if they go to that point, it means they're really after me, in which case they'd decode my VPN communications anyway and I guess they have the means. But I really don't think I'm a valuable target   Their purpose is just to force you to use their paid service...

[Ostracus]

What kind of links are we talking about? DSL? Cellular? VoIP in itself doesn't take much unless you're going HD. Robustness is as good as the underlying link.

[Toulousaing]

sorry for late answer.

Actually, it's a DSL link with very poor bandwith, branded as 128kbps, 256kbps or 512kbps depending on Obi end. But I think that none of them goes beyond 80kbps (if I remember well). Anyway, when I tested the g.711u using best of those links, voice was choppy/broken... Only tests with g.726-16 and g.729 were satisfactory. That's why I'm quite reluctant to try VPN.