STATION ID - 7047/3.12 9x Datakit Network FOR OFFICIAL USE ONLY This is a 9x system, restricted to authorized persons and for official 9x business only. Anyone using this system, network or data is subject to being monitored at any time for system administration and for identifying unauthorized users or system misuse. Anyone using this system expressly consents to such monitoring and is advised that any evidence of criminal activity revealed through such monitoring may be provided to law enforcement for prosecution. &$&$&$&$&$&$&$&$&$&$&$&$&$&$ &$&$&$&$&$&$&$&$&$&$&$&$&$&$&$ &$&$ &$&$ &$ The &$ &$&$ Analogue Cellular System &$&$ &$ &$ &$&$ &$&$ &$ by: Ardist &$ &$&$ &$&$ &$&$&$&$&$&$&$&$&$&$&$&$&$&$&$& &$&$&$&$&$&$&$&$&$&$&$&$&$&$ This TxT file is for ...... 9x..... --- 9x Release only. Introduction: ~~~~~~~~~~~~~ Even though we are at the age of digital technology, the majority of people still are not familiar with the analogue system. This text file has been put out for a better understanding of the differences between AMPS (Automatic Mobile Phone Service) - TACS ( Total Access Communications System ) - and NAMPS ( Narrowband Automatic Mobile Phone Service). Before I continue I would like to thank my good friend AngieB for typing this file out for me. Now that I have explained my purpose for writing this text file I have one more thing to say before we get started: Disclaimer: ~~~~~~~~~~~ This file is for educational purposes only, and anything derived from this file, especially illegal uses of the analogue cellular structure are NOT my responsibility. This file does not contain any information of illegal use of cellular phones or cloning methods. This file is simply for a better understanding of the analogue cellular system. Three Regions of the Analogue System: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Before I begin explaining the three analogue cellular systems I would like to give you a very simple understanding of the three regions the analogue system is divided into. There are three regions. To make this short I am just going to talk about region two. Region two includes North America, South America, and Canada. The three region system is recognized by the International Telecommunications Union ( ITU ). The region two radio frequencies give us the North American AMPS system, which is also known as Nordic Mobile Telephone ( NMT ). Where as in the United Kingdom, TACS system is used in other radio regions. They are all very similar to each other in the sense that they all use Bi-Phase signaling. AMPS and NAMPS systems: ~~~~~~~~~~~~~~~~~~~~~~~ Narrowband AMPS known as NAMPS takes each 30Khz AMPS channel and splits it into three 10Khz channels, the resulting three for one split results in an increase for system capacity. Without the overhead for cell splitting and other complexities that the AMPS system has. NAMPS is compatible with the AMPS system in that the 30Khz control channel is still used,and cellphones can be built to handle both standards. NAMPS has other additional features which makes it a better system. The NAMPS and the AMPS systems are both compatible with the dual mode operation allowing AMPS customers to switch back and forth between the systems,and allowing them to hand over the AMPS channels to NAMPS channels or vice versa. It is possible only if the customer is using a dual mode cellular phone. ARQ ( Automatic Request for Retransmission Signaling ) Signaling: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Automatic Request for Retransmission Signaling. The signaling is at the speed of 200bps, which does away with the 10Khz tone AMPS uses which makes the cellular phone acknowledge orders that it receives from the cellular tower. This is especially important when a handover takes place. Where the AMPS handover order confirmation of 50ms of 10Khz signaling tone is often missed due to interference. Improved Call Control: ~~~~~~~~~~~~~~~~~~~~~~ This is the next feature I will be talking about. The NAMPS specification provides for a feature known as Mobile Reported Interference ( MRI ). The base station (cell site) can request that the cellular phone can send in a measure of the forward Traffic Channel ( TCH ) signal strength. As well as the measure of the number of the errors of the 200bps signaling stream. Alpha-Numeric Message: ~~~~~~~~~~~~~~~~~~~~~~ Alpha-Numeric Message allows the NAMPS system to send fourteen characters or less on the forward channel in a point to point or point to multi-point mode. It also allows you to combine paging functions with your cellular phone service allowing you to send your service provider to charge you more and rip you off, considering that it is a built in system and doesn't cost them anything. Pre-Loading: ~~~~~~~~~~~~ Since cellular phones are dual mode they allow an AMPS phone to support NAMPS technology, without supporting NAMPS service. Sub Audio Signaling: ~~~~~~~~~~~~~~~~~~~~ The key to the 10Khz channel spectrum is the Sub Audio Signaling scheme employed between the cellular tower and the cellular phone. A 200bps continuous data stream is sent. The hacker using the cloned phone, errrr.... the user of the cellular phone does not hear the signaling :o). Because the frequency resides well below the usable portion of the audio spectrum. Superior Audio Tone ( SAT ) and Digital Superior Audio Tone ( DSAT ): ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Taking the place of SAT and signaling tone, is a sequence of digital words in the 200bps stream. NAMPS provides for seven DSAT sequences that have cross correlation properties. Digital Signal Tone ( DST ) consists of the logical inverses of the seven DSAT sequences. Total Access Communications System ( TACS ): ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In the above I didn't mention any specifications of the TACS system. TACS and AMPS are very similar, in fact almost the same. The only major differences in a TACS to AMPS system is Reverse Channel Frequencies (RCF's) and Forward Channel Frequencies ( FCF's ). In AMPS the RCF is 824Mhz-849Mhz and the FCF for AMPS is 869Mhz - 894Mhz. Compared to TACS where the RCF is 872Mhz - 905Mhz and the FCF is 917Mhz - 950Mhz. The number of channels in AMPS is 832 where in TACS it is 1000. AMPS - TACS are the same compared to NAMPS. That is why I discussed AMPS - NAMPS. More Differences Between AMPS - TACS - NAMPS: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ All real differences in the AMPS - TACS - NAMPS systems are very few, which can be broken down into fewer parameters starting with the number of channels. AMPS have 832 channels, TACS have 1000 channels, which is in greater difference with the NAMPS system, which has 832 * 3 possible channels !! There are a few more major differences that I am going to mention, leaving out several. The SAT tones are three at 6Khz for the AMPS and TACS system. Seven DSAT data rate channels is 10Kbps in NAMPS, 8Kbps for TACS, and 200bps on TCH for NAMPS. The TACS system that I have mentioned above is referred to ETACS ( Enhanced Total Access Communications System ). Acronyms and Abbreviations: ~~~~~~~~~~~~~~~~~~~~~~~ AMPS - Automatic Mobile Phone Service DSAT - Digital Superior Audio Tone ETACS - Enhanced Total Access Communications System FCF - Forward Channel Frequencies ITU - International Telecommunications Union MRI - Mobile Reported Interference NAMPS - Narrowband Automatic Mobile Phone Service NMT - Nordic Mobile Telephone RCF - Reverse Channel Frequencies SAT - Superior Audio Tone TACS - Total Access Communications System Disclaimer: ~~~~~~~~~~ This file is for educational purposes only, and anything derived from this file, especially illegal uses of the analogue cellular structure are NOT my responsibility. This file does not contain any information of illegal use of cellular phones or cloning methods. This file is simply for a better understanding of the analogue cellular system. Hope you enjoyed this text file !! If you have any questions you can usually find me on Efnet ( IRC ) in #Cellular, #9x and #IUA :). (IUA) International Underground Alliance --- www.iua.nu --- Be reconized by IUA and be wanted everywhere in the world by Interpol