I am using a Treo 270.

I like to sometimes preface a number with #31# (which is the GSM code that blocks outgoing caller-ID for that call) e.g. if I dial #31#1234567, then the owner of 1234567 won't see it is me calling (to harrass him :-)

I can do this manually without problem but want to be able to use the code in numbers dialled from the addressbook (for people I frequently call but do not want to send my number to as they collect marketing data based on it).

I have managed to do it in the one-touch speed dials as you would imagine, however adding it to the phone number within the addressbook doesn't work, and the Treo instead skips the first bit and dials the number (exposing my caller-ID).

Any ideas?