— Beginning 2011.03.25 and continuing into the next day, SPAM-type calls began hitting my mobile phone. Calls featured unusual, apparently random originating numbers with no accompanying CallerID information. Listed area codes were invalid US area codes. In some cases the “Area Codes” were valid international dialing codes, but internal city codes were generally invalid.
Calling numbers observed in first 24 hours:
280 = MD Maryland “related” code for 240, 301
(Related area codes are area codes that have been split, overlayed,
or otherwise relate to the area code)
355 = Albania; 32 city code = Berat
359 = Bulgaria; city codes: 7, 77, 770 not listed
675 = Papua New Guinea; 42 city code not listed
— COMMENT: Pattern observed by the calls so far would seem to indicate a possible compromised internet-based phone switch and/or use of a zombie net based switching infrastructure. The number patterns used give reason to suspect that they may be generated by a pseudo-random process, perhaps with filtering to avoid valid US area codes.
Published at Tue, 31 Aug 2021 9:20:2 GMT