[solotronics]

I deal with a ton of cell towers interconnected with Ethernet over fiber [ Ethernet point to point built on MPLS ]. I am not sure about cell towers over POTS but I dont think thats how its done now.

Thats not to say there arent legacy towers out there on POTS, but all new towers are on Ethernet via fiber as far as I can tell.

[pak]

Sure, you can connect the towers to the carrier however you want, and this is why certain carriers can sometimes hack in better quality protocols within-network (see the discussion on voLTE further down the page). Carrier-to-carrier connections, however, still have to use POTS/PSTN (since, if you send a voice call to another carrier's network, you can't a priori know it's a smartphone vs. a landline vs. something else right now, and PSTN is the only standard they all agree on). I agree, it's dumb.

Also see https://en.wikipedia.org/wiki/Public_switched_telephone_netw... regarding the 64kbit/s limitation.