Currently, the 1750 does not support IP – IP calling. Since you are talking about a GK, I assume you are talking about H.323. If you can find a GK vendor that supports either GKRCS and empty cap set in H.245 you can achieve this.
If your are talking about MGCP, it would be the functionality of your Call Agent to provide that rerouting functionality.
If you are talking about SIP, then it would depend on the feature server and its ability to fork invites.