Usage of cellphone networks as an alternative to landlines: an option which may make more sense than it would be supposed to

The usage of mobile telephone networks as an alternative to provide a service analogue to landlines in rural areas is, to a limited extent, still relatively common in my homeland Brazil, and to be honest there were times it could address the needs of urban customers too. Sure it would eventually be simpler to use just a regular mobile phone for such service, yet it's relatively easy to find cellphones meant to be used the same way as a landline phone, also enabling the usage as a (usually 4G) internet router according to the data packages available from the carriers. However, excepting some rural areas where the service is subsidized and has no traffic limit, nowadays most mobile carriers only offer data packages with limited traffic requiring customers to either buy additional data packages (also usually with some monthly limit to the purchase of such additional packages) or a decrease to the connection speed which is often worse than the old dial-up connection and then basically leads to an unsuitability for most of the modern usage of the internet. Had the possibility of using the cellphone networks instead of landlines being offered to urban customers with the same benefits, it would be much easier for some users who need portability due to moving more frequently than usual such as military personell, or simply as a better choice than having to wait for a technician to come by and install telephone and broadband internet wiring at a rental apartment in an older building where the entire infrastructure would require retrofits to enable a telephone or internet company to provide the service. As a former user of what used to be known as Ruralcel, maybe I would still be using such service as it seemed so practical when the 3G internet speed was still reasonable for most of my usage at home, and even the reduced speed once I reached the limit remained suitable for a fairly normal usage.