I need to change the master files, not override them. The reason is that many lines contain leftover calls to chan-sip functions, and they generate errors and warnings. A case is the function SIP_HEADER. The only way to solve this is to alter the master file that is used to regenerate the dialplan.
;--------------------------------------------------------------------------------;
; Do NOT edit this file as it is auto-generated by FreePBX. All modifications to ;
; this file must be done via the web gui. There are alternative files to make ;
; custom modifications. ;
;--------------------------------------------------------------------------------;
;*******************************************************************************
; AUTO-GENERATED AND CUSTOM USER DIALPLAN INCLUDED HERE *
;*******************************************************************************
To change them, you would need to modify some of the static files and some of the PHP code, This will break the file signatures, so you will have to disable the code that checks those (not sure where that is) or re-sign anything and provide replacement keys.
In the specific case of SIP_HEADER, some instances are in code which is conditional on the channel driver, so wouldn’t need removing. In fact, I gave up before finding any cases where SIP_HEADER is called on anything other than a chan_sip channel. PJSIP_HEADER, and ADDSIPHEADER are called without pre-checks.
If you, as many do, have both chan_sip and chan_pjsip in use, you would need to add code, to the remaining cases, to conditionally execute the functions.