G3R / Asterisk Integration

Maybe this is a support issue …

I have a large G3R running V9@V3 and we want to know if Asterisk is a possible next generation replacement for our G3R. To walk down that road we would like to start small and work up.

To do that, it seems like running Asterisk behind the G3R is the thing to do. I would like to carve off a small number range and allow Asterisk to manage it. I would like to see it as transparent as possible for transistion, and just grow the Asterisk (if it can do the job) until the trunks come off the G3, analog stations are replaced, and we slide into an all VOIP environment.

Has anyone put Asterisk behind a G3 with some PRI trunking between them? Something similar? Another suggestion?


Yes, I have. Only temporarily, and only to test some VOIP phones we bought to see how good they were.

It’s fairly straight forward. Build a PRI between the two systems, and use UDP to send your extensions to the PRI. Asterisk takes it from there.

There will be different features that don’t translate well, or work at all. Like display data may only work in one direction, (or not at all). Voicemail messages between senders/receivers on different systems can’t be replied to. Asterisk voicemail messages can’t be marked urgent. CDR data is created on two systems now. Your call about the importance of such things.

As far as replacing a system with Asterisk; That’s a tall order. A G3R is a big machine. A good Asterisk box is generally maxed out when it supports 50 or so lines. You’ll need a farm of servers to support the number of lines/trunks with Asterisk that a G3R can. It can be done, but it’s a big replacement.

Some G3R features Asterisk won’t have, or will simulate, or will have to be developed by you. Shared line appearances is new, and doesn’t work on ALL phones. Terminating extension groups don’t exist, but can be simulated. Coverage paths are easy to do with macros but harder if you have a lot of custom coverage paths. (you get the picture)

You suddenly acquire all the maintenance needs of your network services too. Server updates, replacements, backups, etc… All have to be done. Even the phones will need periodic firmware updates.

Each asterisk box, and phone becomes an individual IP address node on your network. Be sure your sub-nets are configured to support that many IP addresses. Will you need to re-wire your building(s)? VOIP uses Ethernet, (and ideally Power Over Ethernet) your current phone station wiring may not be up to snuff. And of course, you need good strong network switches with a proper amount of backbone bandwidth.

And finally, there’s support… You’re it. There’s generally no one you can call to fix your system if it fails. Days, nights, weekends, holidays, etc… you’re the go-to guy. Be sure to factor in the ability of your businesses to tolerate down time while you maintain/repair the system, and your own ability to provide all the maintenance for it.

Good luck.

Thanks for the great overview.

Do you have any info that lists what hardware you used on each end of the PRI and the config files?


On the G3R side it was just a TN464 card. The Asterisk box had a Dialogic board.

Between them was just a T1 crossover cable.

As for config files, that’s for you to build. I’m not trying to be a jerk or anything, but you NEED to know what these files do, how they’re built, and what the settings and changes to those settings mean. They are what make Asterisk work, and it’s ESSENTIAL that you UNDERSTAND it. Modifying these config files is actually how you do your standard everyday moves, adds, and changes. There’s always the option for a real time implementation with database lookups, but that’s your call.

Asterisk is, and can be, a great many things. One thing it is NOT is “plug and play”. It’s best description is a “development environment”. When you first load Asterisk, no “features” exist or will work. You make it all happen by building config files. I’ve built systems that did nothing but post data to websites, and other systems that did nothing but route phone calls. Same Asterisk, completely different functions. It’s all in the config files.

If you’re truly interested in seeing what it takes to get it running and keep it running, I’d advise you to read everything available, and start building your config files yourself. It’s the best way.

A common telecom person now has to be part telecom, part hardware engineer, part programmer, and part network engineer if he/she is going to take on Asterisk.

If you just want to put a toe in the water, the best thing to do is check out AsteriskNow. If you’re serious, you’ll study the config files.

I appreciate your advice.