Change the from header

I’m trying to setup a a trunk with my local provider.

They need the from sip header to be the sip trunk username.

e.g

From: "8239283882"sip:8239283882@X.x.x.x the dummy 8239283882 is the username

how can i change this behaviour ?

currently i’m getting the user end users international name and extension which my provider will not allow this.