Custom ring group behaviour

I’m trying to muck with caller ID on incoming calls to a ring group, but the ext-group-custom context doesn’t seem to get called at all.

exten => 500,1,NoOp(Changing CALLERID from ${CALLERID(all)})
exten => 500,n,Set(CALLERID(name)=${CALLERID(num)})
exten => 500,n,Set(CALLERID(num)=1234567890)
exten => 500,n,Goto(ext-group,500,1)

Should be fairly obvious what I’m trying to do, but watching in Asterisk as the call comes in, it goes straight from from-trunk to ext-group,500,1.

Any suggestions on getting this to work? I suspect it’s just a case of me not grasping how these contexts are included.

Anyone doing anything with ext-group-custom?

If you find out why please let me know. I am trying to do essentially the same thing (append CID number on outbound Ring Group calls).

I am stuck!