AMPS (EIA/TIA-553) and NAMPS (IS-91)
| Mobile Frequency Range | Rx: 869-894; Tx 824-849 |
| Multiple Access Method | FDM |
| Duplex Method | FDD |
| Number of Channels | 832 |
| Channel Spacing | 30kHz |
| Modulation | FM |
AMPS
AMPS (Advanced Mobile Phone Service) was the first cellular mobile system in the United States. AMPS operates as an analog system using 30 kHz wide channels.
NAMPS
AMPS was later enhanced to NAMPS (Narrowband Advanced Mobile Phone Service), a version of AMPS that uses 10 kHz channels and by doing so triples cellular capacity.
AMPS by Any Other Name
Europeans often refer to AMPS as "American Mobile Phone Service." Digital cellular equipment manufacturers and carriers often refer to AMPS as "Analog Mobile Phone Service."
AMPS Standards
AMPS is defined in the EIA/TIA-553 standards. NAMPS is defined in the TIA/EIA/IS-91 standard.
AMPS Network Operators
AT&T Wireless operates a NAMPS network in the United States.
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- Forward and Reverse Channels
Forward and reverse channels refer to a number of frequencies that are used by a telecommunications broadcast system in order for a telephone tower and a cellular telephone to communicate with each other. A forward channel refers to the frequencies used by a telephone tower to communicate with all nearby cellular phones. Contrastingly, a reverse [...]...
- 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 [...]...
- Tumbling
Tumbling exploits a weakness in the AMPS/NAMPS roaming system. In tumbling, you first configure the SIDH in your mobile telephone to pretend to be from another cellular carrier. If you are in Colorado, for example, you would configure your mobile telephone as if it were subscribed to a cellular carrier in Texas. Next, you modify [...]...
- Cell Phone Cloning
Cell phone cloning refers to the act of copying the identity of one mobile telephone to another. This is usually done to make fraudulent telephone calls. The bill for the calls go to the legitimate subscriber. This made cloning very popular in areas with large immigrant populations, where the cost to “call home” was very [...]...
- UHF (Ultra High Frequency)
UHF is an acronym for a band of radio frequencies often used to broadcast television signals. Mobile phones and satellite radio also use UHF signals. The letters ‘UHF’ stand for: Ultra High Frequency. UHF Frequencies Any radio frequency between 300 MegaHertz (MHz) and 3,000 MHz (or 3 GigaHertz) is considered to be in the UHF [...]...