VoIP over Wifi – A Field Report

I think I am renowned for being open to try out new things, especially if they’ve got anything to do with wireless. This time I have even had a practical application in mind. The scenario: Multi tenant flat in Paris, only one phone line, constant search for the phone because somebody has put it where it doesn’t belong, always ending up with the wrong person first when I call in, nightmare each time the phone bill comes in to figure out who made which call, exorbitant prices of the local incumbent, etc. I guess you get the idea. The solution is simple, or so I thought: Wifi VoIP phones have been around for a year or so now. So I figured they would be stable enough by now to be usable over the local DSL line and Wifi Access point as well as fool proof so even a non technical person can just use it like an ordinary phone. Well, so I thought and happily set out to get a Wifi SIP VoIP phone. Reality was somewhat disillusioning.

The Phone and my "Out of the Box" Experience

The market for VoIP phones is still fairly small and there are only a couple of options. As a wireless enthusiast I opted for the UTStarcom F1000G, as its predecessor has been around for quite a while now so it should be fairly stable. The F1000G is a true Wifi phone with an 802.11g chip inside and an embedded web server so the phone is easy to configure once it’s connected to a Wireless LAN access point. I ordered the phone from Sipgate which offers a local number and a prepaid account for free together with the phone. The phone itself is not subsidized and available at Sipgate and other companies for around 130 euros. The phone came pre-configured with only the Wireless LAN encryption key to be configured by the user. Sounds simple, no? Well, it would be if the online description or the printed manual would have given a hint on the password to be typed in to be able to enter the menu via the phone’s screen. Nothing, nada, zip… O.k., well, after trying a dozen standard passwords like 0000, 1234, 12345, etc., I decided to deactivate encryption on my Wireless LAN for a minute to be able to get to the built in Web Server from my PC. Access to the configuration pages, however, is also password protected. Again, the online description and the manual mention nothing about it… But, there’s Google and a quick search revealed the standard password for the administrator account: "psw". This trick worked and I was finally able to set the WPA encryption password and the phone’s password so I can access the security features directly from the phone. Not bad for 45 minutes, except that the whole process should have taken 2 minutes…

Interoperability

A Wifi phone without a WLAN access point and a high speed Internet connection is like a plain old phone without a phone socket to plug it in. The difference between a phone socket and a WLAN access point is the small little fact that one of them has been around for decades and pretty much every phone (country specific…) fits into pretty much every phone socket. I had to find out that the same is not true with Wifi phones. For some reason beyond my understanding, my F1000G phone and Netgear Wireles LAN Access point with built in DSL modem (DG844GB) do not really like each other very much. Voice quality was lousy and every now and then I even lost the speech path completely, especially when going into another room. Not even a software update of the phone and access point resolved the problem. I just don’t get it. Two components, mass produced, millions of them sold and they just don’t want to work together!? I really don’t get it. In the meantime, I’ve tried the Netgear AP with another VoIP product with pretty much the same result. So the phone is not to blame for this one. Anyway, help was near as for occasions like this I have a second WLAN access point with built in DSL modem, a Siemens Gigaset SE515 DSL. So I switched off the Netgear AP and put this on in place. Incredible, the voice quality suddenly became much better and no speech path losses in the next room. Eureka! … and shame on Netgear!!!

Over the Long Run

Telephony over IP is a tough business. Not only do packets have to be sent and received at precise intervals, the equipment and software must be rock solid and not stop working over night. After all, that’s just how ordinary phones act. Unfortunately, not the F1000G with the Siemens Access point. Once a day (or night) or so, the phone suddenly looses contact with the network and refuses to do anything about it. There’s no problem with the Access Point in most cases as the notebook just works fine over the wireless connection. Sometimes the access point dies, too and the whole setup has to be rebooted. Totally unacceptable!

Voice Quality

Voice quality even during long phone calls of 20 minutes was consistently o.k. but far away from the voice quality of a standard phone. Also, other activities on the DSL line while on a call have a negative impact on voice quality. Uploads of eMails with large attachments have a very negative impact on the voice quality in the uplink, while downloading of large files pretty much destroys the experience in downlink direction. Traffic shaping is the magic word, but both of my AP’s do not support this. Simple Web surfing over my 1 MBit/s DSL line on the other hand while being on the call had no audible effects as far as I could tell.

Summary

Well, that phone goes back into it’s box and to the shop. It’s good to see SIP working in a true Wifi phone, it’s good as a proof of concept. For everyday use, however, it is much too instable and until UTStarcom has figured out a way to keep the phone communicating with the network permanently and how to improve the voice quality, it’s a no go for me.

So in the end, I am still stuck with my phone problem in Paris. But I am adventurous, so I gave the Siemens Gigaset C450 IP a try, a DECT phone with a SIP adapter box. SIP terminates in the box instead of the phone which from a technical point of view is inferior to a true Wifi SIP phone. But maybe it’s more stable. But that’s for another blog entry. To be continued…