Hello,
There are a few approaches and use-cases regarding range. I agree completely that MP02s running Serval is a good idea, and can certainly help to extend the range. That would work for less densely populated areas, but would still require fixed infrastructure in the form of the MP02s, and hence phone users would still need to be within about 60m of a MP02 to use the mesh. This nonetheless would be effective in many situations, I think.
Where the population is more mobile, or too sparse for the easy setup of MP-based links, that is where our Mesh Helper devices will become important. These will basically be portable (and soon pocket-sized) MP02-like devices (but without the ATA), and will include a UHF radio for the countries where the appropriate ISM bands are available, which will be capable of potentially several kilometre range, without having to aim links. See the following blog posts for our initial work on this.
On that note, it would be useful to know which African countries support the 430MHz ISM band, and what the particular rules are for each country, if anyone has any information on that.
Paul.