> > What does the TE406 leds indicate? > > Both the ADIT 600 led and the TE406 led are green, the ADIT > has zeros in the error counters. Syslog has this as a final > message after running ztcfg: > > Nov 28 02:31:08 xxx kernel: Registered tone zone 0 (United States / > North America) > Nov 28 02:36:21 xxx kernel: wct4xxp: Clearing yellow alarm on span 1 > > I've seen documentation that says that telco-pots lines use > loop start and I've seen mailing list entries that says you > should use ground start for reliability. Can anyone clarify > this?
Back in the olden analog days, loop start trunks had an issue when calls were simultanously started at each end of the trunk. There was nothing built into the loopstart mechanism to resolve which end got the trunk. As a result, two unknown callers would be tied together, both complaining of wrong numbers. Ground start trunks was a solution to that analog problem, thus making them more "reliable". Other ways to make loopstart trunks more reliable included have one end of the trunks always start using trunks from the low numbered end (eg, 1, 2, 3), and the opposite end start with high numbered trunks (eg, 24, 23, 22). The asterisk implementation of that is "g1" and "G1" for zap channel order selection. In lightly loaded systems the above is generally not a problem. On heavily loaded systems with a reasonable mix of incoming and outgoing trunk calls, loopstart trunks can be a slight problem that is most often addressed through the trunk selection mechanism (eg, g1 vs G1). Pure guess is the ground start functionality was implemented in asterisk due to interface requirements to some legacy systems, and not as a workaround for loopstart issues. If your ADIT 600 has fxo cards in it, the selection of analog loop start vs ground start will likely be dictated by whatever box or central office switch your connecting the analog wires to. Loop start is by far more common in todays telephony environment. Pots lines are always loop start in the US. Keep in mind that in the analog days, trunks were implemented with a series of relays (and other electromechanical devices), and there was little that one could do in terms of controlling signal timing. That timing could range from 100 milliseconds to as much as a second or so depending upon exactly what equipment was used. With T1/E1's, signaling happens in a few milliseconds and does not represent the same problem magnitude. Rich _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- Asterisk-Users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
