Path: utzoo!telecom-request Date: Fri, 12 Apr 91 14:12:58 GMT From: Charles Bryant Newsgroups: comp.dcom.telecom Subject: Re: Is a Data Conference Using Three-Way Calling Possible? Message-ID: Organization: Datacode Communications Ltd, Dublin, Ireland Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 288, Message 2 of 13 Lines: 30 In article leryo@gnu.ai.mit.edu (Leryo Malbito) writes: > Would anyone know how one could set up a data conference using > three-way calling? > [Moderator's Note: You cannot do what you want. The modem has only two > conditions: originate and answer. It cannot talk to another modem set > in the same mode. If you can modify the BBS software and modem it can be done. It is just a multidrop configuration. However this requires that the modems can support this. Depending on the type of modem, it may be possible to kludge something together anyway. If the modems can control whether their carrier is on of off with RTS you can leave the BBS modem alone and take turns transmitting for each of the other two. Since the BBS will echo, this allows each user to see what the other is doing. Note that the BBS will probably hang up when you try to switch between users as there must be a brief loss of carrier, and even if it dosen't some garbage characters will inevitably arrive at the BBS. If you can use an error-correction protocol it could be made to work. Note that the protocol would have to be specially devised, MNP or similar would be no use since the receiver at the BBS must cope with packet numbers from two sequences. Charles Bryant (ch@dce.ie)