Advice about asterisk call centre solution

I have been approached to setup a small call centre. I would like to use asterisk to distribute incoming call to remote locations via voip (eg softphone on remote PC).

We are a predominantly mac environment and the issue of media gateway presents some possible NAT/ Public IP address problems (from what I can gather).

The idea is a number (say 6) of incoming pstn lines will connect to the asterisk server and calls will be farmed out to people in their homes as call centre agents (one incoming line per agent).

The big question is, will this setup work from behind a NAT firewall with one public IP address or will I have to obtain a number of IP address and get rid of my firewall?

Would it make a difference if I used a PC rather than a mac (I want to avoid this if I can)

Media gateways seem hard to come by in Australia (I suspect this will change over the next 12-18 months). What is the best (read cheap) type that a mac user can get their head around and will it work with the Australian PSTN standards.

For 6 incoming lines what broadband speed is optimal?

Are there (NAT) firewall considerations at the remote end?

Or am I on the completely wrong track and i should use a tradional (expensive) pabx?


Short response:
What you want to do, doable, but not as easy as pointing and clicking, but Asterisk is the perfect thing for it.

Not sure why being a MAC environment would be a problem, assuming using ethertalk at least? Really, that shouldn’t be too much of an impact.

You’ll need to ‘host’ those incoming lines. Wildcard TDM400P can handle 4, you’ll need to get the card with 4 FXO modules. Six lines, you’'ll need to get another card.

The setup will work from behind a NAT firewall, provided that the firewall is of reasonable quality to be able to port forward the UDP/TCP packets. This part of the configuration can sometimes be challenging, but that being said, someone with some competant networking knoweldge should be able to muddle their way through it.

I think you want to do yourself a support favor, and get a mid range PC, doesn’t need to be anything too spectacular (something in the 1ghz area with 256meg of ram), and install Asterisk@home 1.5. (put the disk in the drive, press a key to being the installation process, go off, watch 2 episodes of Kath and Kim and when you get back, it will be ready for you to test). The whole thing will be installed and you can immediately begin testing of softphones on your MACs (XLITE from

I’m assuming that when you are talking about a Media Gateway, that you want to route the call to their house via the internet, then convert that IP traffic into a regular phone right? If you are going to route any kind of voice traffic over the internet, you’ll need broadband. Tried it over dialup. Don’t bother. You will be disapointed. Greatly. If they have broadband, give them a softphone, they work just fine. Users can logon to a queue in your asterisk server, accept calls, quality is usually pretty good if the network is up to spec.

The NAT’ing can be a big issue. I’ve run into all kinds of crazy config problems with our remote users with hotel and home routers and the like with SIP softphones on their PC’s. To get around this, I installed a softphone called “FIREFLY” which supports IAX protocol (instead of SIP) which is an Asterisk native protocol. Worms its way through NATs like nobody’s business. Now, firefly is the PC version, but perhaps there are some MAC equivelents.

But if you are looking for Cheap call center…its hard to beat the bang for the buck with Asterisk.

Thanks for that, that is good info.

From what I can gather though, the Wildcard TDM400P or any other NIC is not supported for a mac (may also not physically fit many macs inc the one I want to use) - hence the need for the external Media Gateway as a way of bringing PSTN lines into the asterisk box (as advised somewhere in the asterisk site (but they are working on it:)))

Media gateway Manufactures’ sites suggest that there can only be one media gateway device as all related control and voice ports must be forwarded to that one device. I guess with Asterisk directing traffic, that is not an issue.

I suppose I am seeking clarifcation on my last statement.

As I say I am trying to avoid having to go and buy a new PC but I will if the Media Gateway configurtion is too messy.


I think, simply for support issues, you may want to concider the introduction of a PC to run this. (something built in the last couple of years). I love a Mac as much as the next Mac lover, they are easy to use and install software, but the number of people running Asterisk on a Mac…not many and you’ll find that there would be a lot less response for support for issues you might have.

Besides, do you want to waste a perfectly good MAC on this? Asterisk can be a resource hog and will use as much as it can…the last thing you want to do (no matter what platform you are using) is be using your PBX system to do other things. Get an old PC, they are litterly a dime a dozen, and you don’t even have to know anything about linux to make it work. (Espeically with @home)

Get a PC, drop in a Digium TD400 card(s) and now you don’t have to worry about the Media convertors.

That’s it you’ve convinced me, you’re right I don’t want to waste a Mac and I would be putting myself out on a limb.


Back to Kath and Kim

I’ve used Digium cards in an old G3 running yellowdog linux and they ran just fine. However I would suggest using a cheap PC instead, mostly because that’s what most Asterisk users have their systems running on.

You also may want to consider a channelbank and a T1 card instead of geting multiple analog cards if you are doing more than 4 PSTN lines. In my experience they are more stable and operate more consistently than the PSTN PCI cards.

As for phones, will you be using softphones or hardphones?

Will you also be looking for an agent GUI interface for the people taking the calls?

Initially I was going to usse a soft phone and see how it went.

I haven’t explored an agent GUI

any recommendations?

Softphones are certainly the easiest and quickest to setup(and much cheaper than hardphones) so they are good to start with and see how you like them.

As for agent GUI, depends on what you are doing like if you have a CRM system you want to use. We use astGUIclient and VICIDIAL to handle inbound calls, it grabs the callerid coming in and does a lookup on the number so that the agent can just click on a button to bring their customer record up right when they get the call. Not essential, but the agents like it.