> The Nokia 5110 is a 2G telephone, meaning it uses the original 2G mobile network to communicate. This network has long been decommissioned in most western countries, including Australia.

In Europe, 3G is shutting down, but 2G as a fallback seems to be staying for years to come.

> However, 2G networks were still available as of 2023 in most parts of the world, while notably excluding the majority of carriers in North America, East Asia, and Australasia.

See https://en.wikipedia.org/wiki/2G

AFAIK, in the US, T-Mobile still has a 2G network.