The termination is being done with Switch Telecom (
www.switchtel.co.za).
Some feedback from our trials:
First trial - customer trial:
This trial ran for a week. Data connectivity was provided via a laptop with E220 USB HSDPA adapter and an MTN SIM card. VoIP calls were tested primarily using a softphone on the laptop itself, however, we also provided an ATcom AT530 IP phone handset as well as a LinkSys SPA921 handset for testing. The calls were made during office and after hours and during the week and on the weekend.
The result - client was extremely happy and signed up for permanent service for seven users! Caveat: client used an external antenna at one of the test locations to ensure a strong 3G signal in otherwise weak coverage area; other locations didn't require a special antenna.
Second trial - conducted by myself personally:
I set up a Nokia E70 cell phone with 087 VoIP over 3G service. Note the E70 does NOT support HSDPA but does support EDGE. SIP termination was done with the Nokia's native SIP stack that is part of the default software the phone comes with. I made a few calls from various locations, including whilst driving. I also received a few calls.
Results: In some locations it works pristinely, in others not as well. In general, service at my home (where normal GSM calling often breaks up) was slightly more sensitive to breaking up then normal GSM calls. On the road and at a friend's house where GSM calls were excellent, the VoIP over 3G calls were on a par, if not indistinguishable from a standard GSM call. The cool thing about this setup was that the phone rings for both the 083 and 087 numbers and can dial out either, so at no time was I inconvenienced.
Third trial - conducted by myself: limited comparison of MTN and Vodacom as data bearers. This was only done on one afternoon, so needs repeating, however, initial results were that both networks were mostly on a par (MTN latency slightly lower). Note this was in the context of VoIP (low-bandwidth, delay sensitive), not normal browsing or downloading.
Conclusion: Switch Telecom's VoIP works very well over HSDPA bearer where the signal strength is good. It works reasonably well over EDGE bearer where signal strength is good as well.
We would recommend it for use in fixed-mobile installations (ie. from your home or office but not your car) where signal is strong, or, if signal is weak, in conjunction with an externally wall-mounted antenna to achieve a strong signal. This is particularly useful for people in areas where copper has been stolen and Telkom won't deliver land-line service.
In terms of fully mobile use (as I have been using on the Nokia E70), I believe it is viable for use in conjunction with a phone that seemlessly calls via either VoIP or GSM. While the Nokia E70 works okay, the better solution is something like the Nokia E51 which supports HSDPA as a bearer. I'm going to continue using the E70 in dual GSM/VoIP mode ad infinitum to see how it fares in long-term use.
Note: I have not yet succeeded in making the Nokia E70 swap over automatically between WiFi and 3G bearer. At present, I can chose the WiFi network, or 3G, and swap between them manually. This is a pity, but I'd be interested to see if the newer E51 can automatically swap between WiFi and 3G.
