We have experimented with this! In Liberia we co-financed new cell towers together with the mobile network operator MTN. More info about that here: https://www.givedirectly.org/mobile-phones
Doing more of this is not a priority for us right now, as there’s a very large number of the extreme poor reachable with existing network coverage, but exploring opportunities to incentivise expansion of high quality cell coverage and phone penetration is something we’re thinking a lot about and it’s definitely part of that mix.
On the margins yes, but mostly doesn’t make a huge difference.