The CID Name Prefix is only working for the ringallv2 strategy if prering is used.
This seems to be because the simple-dial macro - which is called e.g. when using hunt and prering - overwrites the previously correctly set CID name. (findmefollow 2.4.14.2)
Code in extension_addtional.conf :
exten => xxx,n,Set(CALLERID(name)=${CALLERID(name):${LEN(${RGPREFIX})}})
exten => xxx,n,Set(_RGPREFIX=)
exten => xxx,n(REPCID),Noop(CALLERID(name) is ${CALLERID(name)})
exten => xxx,n,Set(_RGPREFIX=(xxx))
exten => xxx,n,Set(CALLERID(name)=${RGPREFIX}${CALLERID(name)})
exten => xxx,n,GotoIf($[$[ "${DB(AMPUSER/xxx/followme/prering)}" = "0" ] | $[ "${DB(AMPUSER/xxx/followme/prering)}" = "" ]] ?skipsimple)
exten => xxx,n,Macro(simple-dial,xxx,${DB(AMPUSER/xxx/followme/prering)})
exten => xxx,n(skipsimple),Set(RecordMethod=Group)
exten => xxx,n,Macro(record-enable,${DB(AMPUSER/xxx/followme/grplist)},${RecordMethod})
exten => xxx,n,Set(RingGroupMethod=hunt)
exten => xxx,n,Set(_FMGRP=xxx)
exten => xxx,n(DIALGRP),GotoIf($[ "${DB(AMPUSER/xxx/followme/grpconf)}" = "ENABLED" ]?doconfirm)
exten => xxx,n,Macro(dial,${DB(AMPUSER/xxx/followme/grptime)},${DIAL_OPTIONS},${DB(AMPUSER/xxx/followme/grplist)})
The line with "exten => xxx,n,Macro(simple-dial, ..." is the "turning point"...
Before, the CID name is correct (including the Prefix), after, the Prefix is gone...
I have a fix which saves the CID name and restores it after simple-dial, but I need to test it first.