Can anyone identify this elevator phone?

I am trying to get some information on it.

I was told that the cellular communicator Telguard TG-1B may not work because its lacks a digital dialer.

https://goo.gl/photos/SveMjRRscJNbK3JS7

Its a thyssenkrupp TAC 20

I don't know if this phone is made by thyssenkrupp or some 3rd party company like Viking.

Can anyone identify this phone or know where I can get some specs on it like if it has a digital dialer?

I am basically trying to get this setup on a telguard TG-1B communicator.

Thanks.