I checked this out and found that it is a hoax. For the most part.
McAfee says it's just a hoax.
But Snopes says it has some truth to it. But not for consumers or cell phone customers. Only for businesses that still use PBX to place calls. That means if you have to "Dial 9" to place an outside call, then someone could tap into your line and use it to make long distance calls.
An old article from AT&T confirms this. (via The Wayback Machine) and provides some tips to avoid being scammed.
- This scam doesn't affect residential customers; its target is businesses.
- An AT&T service technician would never call customers and ask them to help check phone lines.
- The scam is generating a lot of interest in the media and over the Internet, but our network fraud experts report no increase in the number of fraud cases as a result of this notoriety.
- The best prevention against this type of fraud is for business managers to make their office staffs aware of it and to review what to do if it happens.
- If someone receives such a call, he or she should ask the "technician" for a call-back number or for the name and number of the caller's supervisor. Then hang up.
- To report this or any other phone scams AT&T business customers should call their account representatives. You also can call the AT&T Business Customer Care Center at 1-800-222-0400, or report the scam to your local law enforcement agency.
Either way, it's never a good idea to do anything online or on your phone that even seems suspicious.