darren@uunet.uu.net (Darren Wyatt Williams) (09/05/89)
Fellow hackers,
I have just purchased a netcomm 1234 automodem and have had
the appropriate telephone line installed. The modem is connected to a
standard IBM-compatible PC running Mirror II communications software.
The problem I have arises when communicating via the modem while the
phone is attached in the handset socket. No problems occur for about
10 to 15 minutes, after which the screen begins to fill with garbage.
I tried out older telephones and found no problems, so the problem
seems to be a fallacy of the new telecom telephones.
Can anyone suggest a reason for this problem and a possible
solution. Any suggestions are welcome.
Thanks in advance,
Darren@murdu.melb.eduvances@xenitec.uucp (Vance Shipley) (09/06/89)
In article <telecom-v09i0346m03@vector.dallas.tx.us> munnari!murdu.ucs.unimelb. EDU.au!darren@uunet.uu.net (Darren Wyatt Williams) writes: >The problem I have arises when communicating via the modem while the >phone is attached in the handset socket. No problems occur for about Do you mean that you have plugged your telephone itself into the modem, in it's jack labeled 'phone'? I assume you do. >10 to 15 minutes, after which the screen begins to fill with garbage. >I tried out older telephones and found no problems, so the problem >seems to be a fallacy of the new telecom telephones. By 'new telecom' I assume you mean an electronic key telephone attached to a business type telephone switching system (a PBX or Key System). > Can anyone suggest a reason for this problem and a possible >solution. Any suggestions are welcome. If my assumptions are correct the problem could be power related. Electronic telephones generally derive their power (for their basic functions anyway) from the lines. Usually the phone has two pairs of wires feeding it; one pair that carries the audio and one which carries the 'data' signalling to run the set. The power (probably -24 volts) is across the pairs. There is no potential between wires in a pair, but between a wire from the voice pair and a wire from the data pair you should be able to measure a voltage (24V). You may have a problem in the modem that is affecting this power transmission. One thing that comes to mind is 'A & A1 control'. This is something that most Hayes compatibles do if you turn it on, and it simply provides a short on the second pair to signal a key telephone system whenever the modem is off hook. Another thing that would cause a problem is the disconnection of the set (the one plugged into the modem) when the modem is in use. This happens on some modems. Vance Shipley uucp: ..!{uunet!}watmath!xenitec!vances Linton Technology - SwitchView INTERNET: vances@egvideo.uucp 180 Columbia Street West (soon) vances@xenitec.uucp Waterloo, Ontario CANADA tel: (519)746-4460 N2L 3L3 fax: (519)746-6884 # if it ain't got an interface it ain't much use! #