Setting up a door phone, what type of channel is a ring group?

I found some posts on how to setup a door phone that will dial SIP extensions. But i’d like to make it ring a ring group so that we don’t have to modify the users in the config file, just in the GUI.

This is the line we are currently using and i can’t figure out what “Type” of channel a ring group is:

exten => s,n,Dial(“SIP/4076&SIP/4073”,)
exten => s,n,Dial(“type/identifier”,)

Our ring group is 2511 and it works from the SIP phones.