Is this mobile phones in North America? If yes, then its easy. Use Cisco Spaces with MR-A licensing and do carrier offload via open roaming for that SSID that will get you ATT and T-Mobile.  no Verizon yet (no comment as to  why 🙄)  Or you could work with 3rd party aggregator like American Bandwidth's WI-DAS and manually config open roaming via MR-E licensing.  If you are talking about doing this for a desk phone. run the Ethernet cables. Even if you have Verizon sim devices, there are ways to install certificates to board them  all with WPA3 and RADSEC ... View more