Modify P-Asserted-Identity header for autodial callee

FreePBX Configuration
2

Add this to extensions_custom.conf and reload

[macro-dialout-trunk-predial-hook]
exten => s,1,Noop()
exten => s,n,GoSub(func-set-sipheader,s,1(P-Asserted-Identity,CUST PAID))
exten => s,n,MacroExit

If you need to apply this selectively based on trunk name, there’s a hint how to do this here: Hooking for fun and income - #6 by lgaetz