A telephone needs a couple of wires and can be powered remotely (those of you who still have basic landlines will recall that they often keep working when the power to your house is out), and is a fantastically simple technology to repair and maintain.
In some parts, mobile phones (AKA cellular phones, AKA handy phones) are leapfrogging landlines because they require even less physical hardware and maintenance - it's not the case that everyone has one; rather, someone has one and sells use of it. People use it to make voice calls.
In the western world (which is really the only part of the world where we can meaningfully talk about technology) the internet connection is usually fast enough, and smart phones are plentyfull enough that it doesn't matter.
Note: Lome is the capital of Togo, not rural or isolated.
> they often keep working when the power to your house is out
Emphasis on the often. If the phone company also loses power, then you don't have phone lines. IIRC this happened during the NorthEast blackout of 2003.