How to forward all incoming calls to a Sip Uri

[imagn]

I am having trouble figuring out how to forward my local did with my provider to a sip URI. I would like to USe 3CX to process all inbound calls and forward them to my voxalot sip number. I have see the options under extension and provider and ring group to forward to an outside number, but only the extension will populate with out an error that the number entered is invalid.

Any suggestions on how to set this up would greatly be appreciated

Thanks