Originally Posted by
dvs7310
I've done this now in countries all over the world, far less developed than SA. If your phone is fairly recent then the GPS should work even without a cell signal, so as long as your phone has already downloaded the base maps then you're fine even in desolate areas.
Personally in SA I like MTN best. I think Vodacom is just as good but I couldn't get their SIM card to work in my Galaxy (it's unlocked but is temperamental with a few companies' cards. This last trip MTNs computers were down so they couldn't sell a card when I arrived so I went with CellO... it was bloody awful. 2G through most of the eastern part of the country which is ridiculous when you need your map to update.
The danger of relying on cached maps is that if your phone clears its cache - which can happen almost randomly - and you have no mobile signal then it can't fetch more maps and you're in trouble. Obviously this does not apply if you're using a true offline maps solution (Google Maps offline, Open Streetmap maps downloaded to your device, TomTom app, etc).
I chose Vodacom because I was going into the Kruger NP and other rural areas where coverage could be marginal, if you're not going right into the edges of mobile coverage than MTN would be fine - I was just trying to get the best coverage I could.
I found that the 2G coverage was often quite workable, unlike in Europe where 2G usually means you're at the edge of 3G and 2G coverage with 3G failing just before 2G. In South Africa I often had solid 2G coverage that would transmit data at 2G rates, good enough for maps, in rural areas.