Raj Jain wrote: > On Mon, Nov 10, 2008 at 6:56 AM, Tony Mountifield > <[EMAIL PROTECTED]> wrote: > >> Does anyone here know anything about GEN-GEN analogue circuits, also >> known as Manual Ring-Down (MRD)? Apparently they are widely used in >> Hoot'n'Holler systems for financial dealer-boards. >> >> I have been asked to try and interface to such circuits, and have been >> having great difficulty locating any specifications for the interface. >> >> Apparently, they are always-on 2-wire analogue circuits with no tip >> voltage or loop current, and on-demand superimposed ringing voltage in >> either direction for signalling (to do nothing more than get the remote >> end's attention). >> >> I was wondering whether it is possible to adapt an FXS or FXO port to >> operate in such a mode, but I'm not optimistic. >> > > Your understanding of MRD is correct (these are nailed-up connections > with only ring-gen capability). I've personally not tried this w/ > Asterisk FXS/FXO ports but If you can make it work that way pls. let > us know. > > -- > Raj Jain > > The MRD telephones uses local battery, that is the reason why they do not have loop current (central battery). Any adaptor to a FXS circuit is useless because there are not any signalling to indicate on/off hook. Just the initial manual ringing. Then working on FXS ports is almost impossible or very expensive. Another approach is to use E/M signalling. The audio channel could be open permanently and transmit the ringing over the E/M wires. You need a ringing detector and a ringing generator in both sides. Take care of isolate the audio channels from the ringing current. I do that many years ago on PCM muxes with E/M interfaces. The Multitech gateways have E/M interfaces, but never tested under this conditions. Obviously, the easy way is to use two standard sets working as hotline.
Jorge Mendoza _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
