For internet access - sure. For messages - sort-of. For calls - troublesome. As far as I know, smartphones don't have a protocol for accessing a remote cellula

For internet access - sure. For messages - sort-of. For calls - troublesome. As far as I know, smartphones don't have a protocol for accessing a remote cellular network connection in the same way as if it was internal, so the only viable way is to have a hotspot device that shares the connection over wi-fi.