No idea if those skills would be transferable. I was on the small to mid sized biz side. Never worked for a provider or anything. Mainly managing, installing and configuring systems.
Once you understand the basics of telephony it’s pretty easy. It’s getting more complex now since it’s all ip/sip based but because that’s a skill that is lacking because everyone who does know that wants to be a network or security guy, not the phone guy/gal.
If you are working it now. Figure out who’s doing your phones and express interest in learning. It’s how everyone I know got into it.