iI its a 433 gateway you can use an RTI T1B OR T2i and load crestron RF codeset into it. it will need programming both in RTIs Integration Designer Software and in Crestron Simpl.

This assumes you have access to the un-compiled Simpl program files.

If the gateway is 418 then there were some URC remotes that can also be programmed with Crestron RF codes, although I seem to remember there were some join numbers that needed to be avoided with the URC solution.

I have done many, many RTI remotes with Crestron (as the ML 500/600 solutions from crestron were simply terrible!), and two systems with the URC.

All have been rock solid until the remotes finally die!