Browse Prior Art Database

METHOD FOR CALL WAITING SERVICE IN A TWO WAY CT2

IP.com Disclosure Number: IPCOM000007421D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2002-Mar-25
Document File: 3 page(s) / 135K

Publishing Venue

Motorola

Related People

Prashanth Gowda: AUTHOR

Abstract

Call waiting is a supplementary service which existing PSTNs already provide for wire-line phones and mobile phones. If the telephone subscribes to this service and if there is an incoming call while the telephone is busy, in-band signalling in the form of short beeps are introduced into the voice channel of the called user. (The calling user hears a ring back instead of the normal busy tone). Called user can switch between the two calls using the "flash" (recall) function.

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Technical Developments

METHOD FOR CALL WAITING SERVICE IN A TWO WAY CT2

by Prashanth Gowda

PRIOR ART:

  Call waiting is a supplementary service which existing PSTNs already provide for wire-line phones and mobile phones. If the telephone subscribes to this service and if there is an incoming call while the telephone is busy, in-band signalling in the form of short beeps are introduced into the voice channel of the called user. (The calling user hears a ring back instead of the normal busy tone). Called user can switch between the two calls using the "flash" (recall) function.

  In a one-way CT2 we can make outgoing calls only. So call waiting by definition does not exist. In CT2 two way system this service can be provided.

  In both wire-line and mobile telephony this serv- ice is implemented in the telephone switch. In the CT2 Two Way system referred to in this disclosure (see [l] and [2]), the PSTN switch routes the calls to CT2 handsets based on a TCAP number translation procedure. This translated number is actually a direc- tory number belonging to a base station. The base station appears as a subscriber equipment to the switch. Subsequent calls coming to this directory number may not necessarily be meant for the same handset. Thus the switch can not use the conven- tional methods to implement call waiting supple- mentary service in this system.

  Now consider the scenario with 3 parties for sim- plicity. (The method can actually handle any num- ber of simultaneous calls subject to the availability of bearer channels). A portable (Party A) is in con- versation state with party B (outgoing or incom- ing call). Now if there is an incoming call for the same party A from a subscriber C, the base station checks to see if the portable subscriber has call wait- ing service. If that is the case, it will send an appro- priate sequence of SIG IEs defined in the CA1 pro- tocol to alert the portable of the second incoming call. It will also update the handset display with the CL1 (subject to availability of CL1 for presentation and portables' subscription info). Based on the CL1 the user can choose to reject or accept the call from party C. If the base station receives recall (flash) "Feature Activation" From the portable, it will sim- ply switch the voice channels to connect the party C through to the portable. Subsequent recall FAs will act as toggle function to switch one of the 2 calls (party B or party C) through.

  Thus call waiting is implemented here without the need for any support or supplementary service horn the PSTN.

DESIGN DESCRIPTION:

The method described here makes it possible to

provide call waiting service for a CT2 Two Way call- ing system.

  When there is an incoming call for a valid CT2 Two Way subsc...