Hide outbound caller id number

For the life me i cannot turn off the outbound caller displayer number, i use voipcheap.co.uk for landline calls and mobile calls but i dont want my number to display to the person i am phoning as i have a different incoming number, i have tried entering hidden in trunk cid, the extension Outbound CID, and also tried overriding in the route option to no avail.
my voipcheap peer details
disallow=all
context=ext-did
dtmfmode=rfc2833
fromdomain=sip.VoipCheap.com
fromuser=445601xxxxxx
host=sip.VoipCheap.com
insecure=port,invite
qualify=yes
secret=mypassword
type=peer
username=myusername
allow=g729

i am probaly missing the blatently obvious
any help would be great

Does your provider allow you to change CID?

BF

the format is very explicit.

It should be:

“hidden”

that will trigger specific dialplan which will execute this statement:

exten => s,n(hidecid),ExecIf($["${CALLERID(name)}"="hidden"],SetCallerPres,prohib_passed_screen)

assuming your provider honors the signalling, this is what tells them not to display the number while still passing it to them.

Some provider will require a setting of “sendrpid=yes” but you would have to find that out from your provider.