bob@semantic.UUCP (07/31/90)
In <2247@anomaly.sbs.com> mpd@anomaly.sbs.com (Michael P. Deignan) writes: >I've got an interesting problem with my Telebit Trailblazer Plus which >I'm wondering if anyone else has run into. > >The modem will perform flawlessly on incoming calls. No problems, answers >like a charm. > >However, on outgoing calls, there are times when the modem will appear >to be "deaf". That is, although I can hear a remote system's carrier, >the Telebit will sit there, not answering with a return carrier to >establish a session. And tts@tut.cis.ohio-state.edu (Karl Bunch) replies: >I had a friend that had this same problem. It seems he put a cheap phone >on the Telebit (T2500) modem (Phone Jack on back of modem) and when you >dial-in the phone doesn't affect the connect but on dial-out it will >make your modem act deaf. > >My guess is that on dial-out the relay doesn't cut the phone until last >min. whereas on dial-in it cuts the phone out when the modem goes off hook. And I add: Remembering back now I once had a very similar problem with a TB+. In coming calls worked great, but on out going calls the TB+ would act deaf, or just fail to negotiate a connection. I could however connect to locally dial low speed (2400 baud or less) modems. This drove me NUTS and Telebit tech support was clueless, they kept blaming the phone service. Well my problem was solved by moving the physical location of the modem. It was previously placed on top of a an unshielded CPU, next several multiplexers (sp?), and a HUGE rats nest of cables. I put the modem in the draw of a metal desk, and Presto it was no longer deaf! My only guess was either, somewhere in the modem a whole bunch of interference was being received, or that in moving the modem the cables (including phone lines) where moved out of the way of any interference they where picking up. Now Karls' idea about the cheap phone may be correct. The cheap phone may have been acting as an antenna for interference. I'm a software programmer not an electrical engineer, can anybody elaborate on my theories? -- Robert A. Gorman (Bob) bob@rsi.com Watertown MA US -- -- Relational Semantics, Inc. uunet!semantic!bob +1 617 926 0979 --