Hi @Bond22, thanks for your post here in the community.
As @nodrogd has mentioned, even though the connection goes through your Hub for 21CV/DOCSIS landline technology, it's not routed via the internet so this is unlikely to work I'm afraid.
The only way this will work is if there's an appropriate slot in the handset's base where you can connect the 21CV lead into.
Even though this may be a disappointing response, I hope this has helped.
Many thanks
Tom_W