No signal - route SMS via Wi-Fi?

[#1]

I have no mobile phone signal but I do have a Wi-Fi connection. Is there a way to route SMS to the mobile network via a Wi-Fi connection to the Internet? It seems like it should be possible; they already interface to provide mobile Internet access.

[#2]

https://community.plus.net/t5/Mobile/Wifi-call-on-Plusnet-Mobile/td-p/1390740