Adding 100TRYING on registration reguest, is this easy to change somewere?

Does somebody know’it is easy to let the freepbx respond with 100trying on a registration request first before it send the 401 Unauthorized message?

we have an device, which requires first the 100 Trying before the 401 Unauthorized is received.

anyone an Idea how to switch on this 100 Trying message?


Here are some comments from Jira on provisional responses.