Its secret is shrewd use of the antiquated telecom language Signaling System No. 7, known as SS7, that phone carriers use to route calls and text messages. Any entity with SS7 access can send queries requesting information about which cell tower a phone subscriber is nearest to, an essential first step to sending a text message or making a call to that subscriber. But First Wap’s technology uses SS7 to zero in on phone numbers and trace the location of their users.
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