One of the most vexing issues in telecommunications today is the proliferation of unwanted telephone calls. Most unwanted telephone calls are unsolicited attempts to sell goods or services. Oftentimes, a computerized calling program is utilized to place thousands of calls. This practice has been dubbed “robocalling” and is the subject of numerous complaints to government agencies like the Federal Communications Commission (FCC).
Those that employ robocalling have gotten more sophisticated in their approaches mainly through the use of caller ID spoofing. Caller ID is the mechanism employed by virtually every telephony service provider that identifies the telephone number of the calling party to the called party. The intent is to provide the called party with knowledge of who is calling when deciding whether to answer the call. Spoofing refers to the practice of altering the caller ID field of an outbound call to mask the true identity of the calling party. Typically, the robocaller will alter the area code and perhaps the local exchange portion of the calling telephone number to make the calling party appear to be a local call. Anecdotally, people are more likely to answer a telephone call from the same area code than from a distant area code. Any changes to the caller ID field mask the true identity of the calling party and deceive the called party. It may be argued that if a called party could actually trust the caller ID on an inbound call, they could more effectively screen their calls answering only the ones they were most confident were not unsolicited robocalls.
What is needed are techniques for verifying the caller ID field of an outbound telephone call is indeed the telephone number associated with the calling party.