> I am planning to connect my Asterisk PBX to one or two POTS > lines, and am wondering if it is better to use a TDM card for > this, or one or two SIP devices with FXO ports on them (such > as an SPA-3000, Grandstream 488).
I think it largely depends on where you're located and how much work has been done supporting phone lines in your area. I've used all 3 of the devices you mentioned in the UK, and here are my thoughts: HT-488: Initially very promising - no noticable echo, seemed to detect hangup cleanly, etc. when I tested them late evening at a client's place. The following day, no end of complaints from the client - it seemed the 488s were only picking up about one call in three, the others weren't picked up at all. Tried upgrading the firmware, but this had the side-effect of making the 488 answer the call before passing it into Asterisk (so the BT ringing sound disappears, call answered by the 488, then it generated its own ringing tone for the caller) which wasn't acceptable to the client. Found that the units needed restarting a couple of times a day to get them to pick up incoming calls again. SPA-3000: I have one of these on my home phone line since it's some distance away from the asterisk box. It's been there for about 4 months now and I've had no reliability problems at all. It seems to detect hangups fine, doesn't hold the line open for extended time periods, etc. There's plenty of forum posts out there detailing what settings to change for different countries. I found those very helpful when configuring the thing for a BT line. Other thing to note - you will have to spend quite some time configuring the PSTN gain levels - when I first used the thing callers could barely hear me at all. There is still minor echo at some times during calls from/to PSTN, but I think this is probably because I've had to adjust up the gain level so much. Apparently this is fixable in later firmwares, but I've failed miserably to update this one recently. Picks up UK caller ID perfectly. TDM: Definitely the neatest solution, especially if you need multiple PSTN lines. Probably works perfectly for US-type phone lines, but I've had no end of difficulties getting it to recognise UK CLID. Doesn't seem to detect UK hangup in more than about 30% of cases and the lines don't drop until a good minute or so after the caller has hung up. If you have one line, I'd suggest the SPA3000. If you think you're likely to expand it *and* you're going to be in a country where the TDMs are known to work fine, then that's a neater solution than lots of ATAs around the place. Regards, Chris -- C.M. Bagnall, Director, Minotaur I.T. Limited This email is made from 100% recycled electrons _______________________________________________ --Bandwidth and Colocation sponsored by Easynews.com -- Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
