How does the OBiTalk point-to-point protocol work?

[restamp]

I understand the basic principles:  Every OBi device has a unique 9-digit OBi Number and when you "dial" another device's number using the OBiTalk interface, your device establishes a connection to the remote OBi so that the two parties can talk directly.  But how does it determine where the far-end device is in the network?  (How does it figure out its IP address?)

Is there some special clearing house that all active devices check in with?  If so, I suspect they need to employ keep-alive packets to keep any NAT session tied up, right?  Presuming this is the case, do the voice packets also go through this intermediary, or do they flow directly between the calling and called parties?

Inquiring minds want to know.

[drgeoff]

Are you sure that an Obitalk call is point to point?

The OBi servers know the IP address of all OBis that are registered with them and on-line.

[restamp]

Well, no, I'm not sure.  I want to find out.  That's why I asked.

[azrobert]

The call goes to the OBiTalk servers then to the target OBi. When you add your OBi to OBiTalk it gets "registered" to their servers. Now your OBi can be contacted or you can contact any other OBi connected to the OBiTalk servers, not just your devices. When you add a device to the Circle of Trust, it can reach your Auto Attendant, but with the default configuration other devices can still call you if they know your OBi Number. This is why you need to be careful when configuring your OBiTalk network.

[restamp]

Thanks azrobert.  Two questions:

1. If you don't register your OBi device with the OBiTalk portal, does it still register itself with the OBiTalk servers when it comes up to the extent necessary to permit you to receive and make calls (presuming the OBiTalk Service default of "Enabled" is not changed locally)?

2. So the call setup packets, of course, have to flow through the intermediary OBiTalk servers.  But, after the call is set up, do the voice packets flow through the OBiTalk server, or do they go directly from the calling party's IP address to the called party's IP address (and vice versa)?

[azrobert]

1. I did some testing a long time ago. I deleted one of my devices from OBiTalk and was still able to do an Echo test, but a call to my other OBi failed. I then added the device to a 2nd OBi account. Now I was able to call the other OBi device. I don't know if anything has changed since my test.

2. I think the packets still flow thru the server, but I'm not sure. Maybe someone else can definitively answer your question.

[ianobi]

2. So the call setup packets, of course, have to flow through the intermediary OBiTalk servers.  But, after the call is set up, do the voice packets flow through the OBiTalk server, or do they go directly from the calling party's IP address to the called party's IP address (and vice versa)?

The OBiTALK network uses what appears to be a proprietary form of SIP. The signalling sets up the call via the Obihai servers, then the RTP packets use the most direct route possible, as with a normal SIP call. If you have two OBi devices on a local network and dial from one to the other, then the RTP packets clearly show as staying within the local network.