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IMPROVED SUPERVISION ALGORITHM FOR TELEPHONE INTERCONNECT IN TRUNKED RADIO SYSTEMS

IP.com Disclosure Number: IPCOM000007324D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-14
Document File: 4 page(s) / 199K

Publishing Venue

Motorola

Related People

Richard Ng: AUTHOR

Abstract

The algorithm provides an improved method of Answer Supervision and Disconnect Supervision (forced disconnect) on loop start telephone lines for new trunked telephone interconnect systems (such as IntelliRepeater telephone interconnect, or Start Site CIT) over the current method used in today's CIT and MBX systems. Answer supervision is the feature that is used in telephone interconnect sys- tems, such as the CIT and MBX, to determine when a radio to landline call has been connected through and when billing of the call is to begin. Likewise, disconnect supervision is the feature that determines when the landline caller has disconnected (hung up) so that the interconnect channel can be efficiently dropped and to prevent unauthorized reuse of the telephone line. This algorithm could be implemented using digital signal processing algorithms or by analog/digital hardware on new trunking telephone Interconnect products to produce improvement over the existing methods.

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Technical Developments Volume 24 March 1995

IMPROVED SUPERVISION ALGORITHM FOR TELEPHONE INTERCONNECT IN TRUNKED RADIO SYSTEMS

by Richard Ng

SUMMARY

  The algorithm provides an improved method of Answer Supervision and Disconnect Supervision (forced disconnect) on loop start telephone lines for new trunked telephone interconnect systems (such as IntelliRepeater telephone interconnect, or Start Site CIT) over the current method used in today's CIT and MBX systems. Answer supervision is the feature that is used in telephone interconnect sys- tems, such as the CIT and MBX, to determine when a radio to landline call has been connected through and when billing of the call is to begin. Likewise, disconnect supervision is the feature that determines when the landline caller has disconnected (hung up) so that the interconnect channel can be efficiently dropped and to prevent unauthorized reuse of the telephone line. This algorithm could be implemented using digital signal processing algorithms or by analog/digital hardware on new trunking telephone Interconnect products to produce improvement over the existing methods.

viding a method of disconnect supervision. In today's trunking systems that use CIT or MBX, a channel could be hung for the duration of the interconnect call timeout period whenever there is an interconnect call (i.e., mobile-to-land, land- to-mobile, and land-to-talkgroup). This occurs

when the landline caller hangs up (for mobile-to- land or land-to-mobile calls) and the mobile user forgets to terminate the call from the radio. For land-to-talkgroup calls, there is no method for determining when the landline caller has ended the call. Only the interconnect timeout period is used to terminate the call.

3. This algorithm will provide more accurate billing of interconnect calls over current implementation used in CIT and MBX systems when central olhce answer supervision is not provided on loop start or ground start telephone lines. The MBX and CIT currently uses a programmable answer thresh- old timer to determine when to begin billing of mobile to landline call. With this implementa- tion, a mobile could be billed for an unconnected call (when landline is busy or does not answer and answer threshold time is exceeded) or not get billed for a completed call (when duration of completed call is less than answer threshold time).

PROBLEMS SOLVED

DESCRIPTION OF ALGORITHM

The following problems are solved by the imple- mentation ofthis algorithm:

1. On loop start telephone lines, this algorithm will prevent unauthorized reuse of the telephone line by mobile-to-landline interconnect users. In today's trunking system that use CIT/MBX and loop start telephone lines, mobile users can make unauthor- ized interconnect calls on certain PSTN/PBX exchanges, This usually occurs when a mobile initially completes an authorized interconnect call to a landline user. ABetwards when the landline hangs up, dial tone may return to the mobile...