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    • How to Unlock a BlackBerry

      How to Unlock a BlackBerry

      Many wireless providers across the globe, including AT&T/Cingular, T-Mobile, Vodafone, and Verizon sell Blackberries. When these companies sell a BlackBerry, they do so at a discount in order to attract customers. The providers then make up the lost profits over the lifetime of their contract with the customer. To protect those profits, the wireless providers

    • Loop Start

      Loop Start

      Loop start is a a signaling technique in which a party gets a dial tone by closing (shorting) a DC current loop. In a loop start signaling system, the electrical loop between your telephone and your central office (CO) is normally open. When you pick up the telephone handset, it causes a circuit to be

    • DTMF (Dual-Tone Multi-Frequency)

      DTMF (Dual-Tone Multi-Frequency)

      DTMF tones, or Dual-Tone Multi-Frequency signaling, are audible tones that are used by touch-tone telephones to identify which number key was pushed by the operator. DTMF tones have been used since 1963 and are used by all standard touch-tone telephones in the United States as well as in many other countries around the world. DTMF

    • NAM: Number Assignment Module

      NAM: Number Assignment Module

      The NAM (Number Assignment Module) is the EPROM (Erasable Programmable Read-Only Memory) in a mobile telephone which holds information such as the MIN (or MDN) and SIDH.  The data fields stored in a phone’s NAM vary between the various mobile telephone specifications, such as AMPS/NAMPS, GSM, PCS, CMDA.  In modern networks, NAMs can be reprogrammed

    • IS-54 and IS-136: TDMA

      IS-54 and IS-136: TDMA

      IS-54 and IS-136 are standards for TDMA American Digital Cellular. Mobile Frequency Range Rx: 869-894; Tx: 824-849 Multiple Access Method TDMA/FDM Duplex Method FDD Number of Channels 832 (3 users per channel) Channel Spacing 30Khz Modulation DQPSK Channel Bit Rate 48.6Kb IS-54 and IS-136: TDMA Security IS-54 and IS-136 use the CAVE (Cellular Authentication, Voice

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