Radio spectrum is precious, so virtually any type of radio telephony is significantly compressed, either in terms of raw audio bandwidth or by applying lossy digital compression — often both. This applies to both 2-way radio and cellular telephones.

There are radio-fax standards. Marine weather reports are a good example that's still in use: https://en.wikipedia.org/wiki/Radiofax

However, the fax machines we use on our telephones were not designed with this in mind. The protocol is neither tolerant of the reduced bandwidth nor lossy compression from cellular networks... not to mention jitter if the call passes over a packet-switched network.

The codec used in calls to landlines disallows the bandwidth required.