Telco's providing Caller-ID have been required to also provide the ability for a calling party to suppress the Caller-ID signal. Generally this is done by pressing star-six-seven, or 1167, before making the call. Centrex customers often use *97, or 1197 . In most cases this will block the next call only however some Telcos have decided to implement this in a bewildering array of methods. The best answer is to contact the service provider and get an answer in writing.

Currently this is supplied as either by-call or by-line blocking. By-Call is preferred since the caller must consciously block the transmission on each call. By-Line blocking as currently implemented has the disadvantage that the caller, without having a second caller-id equipped line to use for checking, has no way of knowing if the last star-six-seven toggled blocking on or off.

Note that blocking is provided by a "privacy" bit that is transmitted along with the CNID information and so is still available to the Telco switch, just not to the subscriber as a CNID signal. Consequently related services such as call trace, call return, & call block may still work.

Found floating on the net, originally compiled by Padgett Peterson padgett@tccslr.dnet.mmc.com

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