Initial review of the Nokia N93 VoIP features

The Nokia N93 is clearly one of the most advanced 3G phones available in the market as of today. It comes with an extensive connectivity support via GSM, WCDMA, WiFi, Bluetooth and Infrared connections. One of the most interesting features that made me buy this phone is the availability of WiFi along with a SIP stack. Do not expect however that setting up a N93 for VoIP calls over WiFi is for common mortals. It takes some serious hacking to finally get the WiFi connection up and running and the SIP connectivity configuration to work correctly.

The first thing that seemed unnatural to me is that the WiFi connection setup is not as you may expect part of the "Connectivity" set of configuration applets but rather part of the "Tools->Settings->Connection->Access points" screen. I would say that Nokia did a really good job making it so difficult for users to find that configuration screen. One you got that, it is a pretty usual way of setting up a WiFi connection. I have only used it with WEP security and it worked fine for me in that mode. Surfing the web over WiFi from your N93 is great and I thought that Nokia did a great job with the integrated web browser in their 3G phones.

As the N93 comes with a complete SIP stack that is supposedly ready to allow you to use the N93 over an all-IP network to establish SIP sessions for voice calls and other SIP based interactions, it immediately assumed that such a thing would work pretty fine with the WiFi access point. The SIP configuration setup is clearly not an obvious thing for common users but it is pretty straightforward for anyone familiar with SIP network architectures (or 3GPP IMS by the way) and the SIP protocol. Accessible from the same place than the WiFi Access point configuration, you can start using it by creating a new profile.

A couple of things that I found out through ethereal traffic captures and multiple tests in different configurations may save you some time:

1. First and foremost, you can not establish any SIP session unless your registration was successful. Honestly this has nothing to do with the SIP protocol itself but is rather a way of ensuring some control over what things you can do with your N93 phone. Mandatory registration makes it more difficult for common mortals to just use the N93 to make VoIP calls in a P2P configuration without going through a SIP or a 3GPP IMS infrastructure.
2. You can not have a successful registration unless the SIP proxy and the registrar server (or the CSCF) are in the same subnet than the IP address that you obtained via the WiFi access point. Again, this is simply another restriction to ensure that you can not freely use your N93 to make VoIP calls. By restricting the registrar to be in the same subnet than your N93's IP address, you are forced to register with a server in the WiFi service provider's network. It appears to me that Nokia has integrated WiFi and VoIP over WiFi only to meet the needs of enterprise customers for calls made only within the enterprise's WiFi network or for a combined offer of WiFi and other access networks from the same service provider.
3. You need to specify the registrar and the proxy addresses as a SIP URI and not simply as an IP address. The registrar server URI should be "sip:domain" where domain is just your domain name not including the host name. In general this is the same thing than the realm.
   
4. There is no integrated SIP phone client in the N93, so you need to find one or you need to create your own Symbian client :)

I have only tested the IETF profile and not yet the Nokia 3GPP profile of the SIP stack. Soon I will be testing the phone SIP capabilities to establish SIP sessions both in an IETF SIP network architecture as well as in a 3GPP compliant SIP architecture. As I could not find a usable free SIP client, I will be using one of our own IMS application clients for Music Sharing.

Stay tuned....