What hardware do I need?

I have got a nice P4 system w/ 512mb of RAM for my Asterisk server.
I have three POTS lines coming into the church where I work, one is a dedicated fax and I would not even bother running it through the system. That would leave the other two POTS lines needing to be integrated into the system. My question pertains to the fact that I cannot find adequate documentation on the “how-to” side of configuring the hardware.

I know that I need to a two port card to bring the POTS lines to the server, but then how does the VoIP then propegate across the network to the IP phones? I have an Avaya background and we always had to have a “home run” from the server room to wherever the IP phone was located, if it was not a “home run” then an AC adapter had to be used as standard network switches would not pass POE.

I see this card on Digium’s site: Digium TDM410, obviously two of the ports would be used for the POTS, but what about the other ports? Do I need one port per IP phone or am I just plugging into a standard switch and using an AC adapter? Some help please, or if there is adequate documentation please forward me to that as I don’t mind reading.


Hi Ryan,

You are right in thinking about a switch and a power adapter. May be you could do it with a hub itself.
The IP phones should be part of local LAN (the TDM cards have no place for them). For your network,
TDM422E could be a best bet as it supports 2x FXO (for your POTS) and 2x FXS ports (for analog sets).


I would not have any analog sets, strictly IP phones. That is why I was wondering how people were normally setting things up as my only experience dealing with Avaya technology was utilizing their appliances to send POE to the IP phones.

Is there a specific card that connects the server to a network switch so that there is connectivity with the phones? This is something I can’t find documentation about. Aren’t all the ports on that card reference above RJ-11 vs. the RJ-45 needed for IP phones?

I don’t know how much your church is paying for each PSTN line. If it is a lot, perhaps you should tell the church to consider moving to VoIP and forget about investing more on FXO hardware. Once on the VoIP world, intergrating Asterisk PBX system is a breeze even on a Linux embedded system. I have my Asterisk PBX system hosted on a long discontinued Netgear WGT634U and it has been running flawlessly. let alone it consumes less than 10Watts of electricity with no noise and small footprint. If you use a P4 computer to host your Asterisk PBX system, it will cost more for operating cost with its noisy fan.

I understand the need to move to VoIP, that is the direction I am moving towards. In the meantime though, does anyone have information on integrating the asterisk server into an existing network? Seems like everyone has a portion or another idea which is great, but I really would like to know how I would set it up as I’ve layed out. I know how to bring the POTS lines in, but how do I then propegate them out?

As you are insisting on going ahead with the already existing setup, Yes…,
you need those FXO cards to connect your anolog lines to the VOIP system.

As for us your IP phones are concerned, decide on how many hard phones
you require and get them. Again i am saying, am not good at the pricing.

The IP phones should be in the local LAN. Extend that and plug the IP sets.
It could be a Switch or a HUB. Try to explore the LAN expansion alone.
The IP phones would not require any special hardware apart from that.


I’m looking at a doing a similar setup and while I’ve not done much with Asterisk you shouldn’t need anything but the FXO cards, server, and phones. The cards with bring the POTS lines into the system, the system will be on the LAN, and the phones will be on the LAN. Now in some commercially designed systems I have seen the phones auto discovered and downloaded their settings from the server or sometimes they needed to be setup with the server IP, etc.

However, like I said I am just getting started with this so I’d actually like some feedback. Does that sound right?

Hi Ryan,

Regarding the phones & what hardware to choose, others might help you with.
“Asterisk: The Future of Telephony” would be handy and help you understand.

In my view, you are on the right path and the right forum is here to guide you.
Your setup will work out well in the way you wanted. Start with the installation
and get back to us with any specific issue that might arise (hopefully it would).