SIP Gateway / Interface Card

Here’s my proposed architecture:

  • 3 incoming analog phone lines
  • 1 good server running asterix (or another IP PBX)
  • 10 telephone stations

My question lies with how I connect the 3 analog phone lines to my Asterix box. I’m confused as to the devices out there:

I understand that manufacturers of “Analog Interface Devices” with 3-4 FXO cards from Digium, Sangoma, and Rhino can be put into the Asterix box and presto all should be good.

But what I would like to understand is how about using a “SIP Gateway”, such as the Mediatrix 1204 (, AudioCodes MP-114 (, or VegaStream 50 6x4 ( Can I use one of these “gateways”, even if they offer no additional benefit, instead of the “analog interface devices” above?

The reason I am interested in these products, is because I would like to evaluate 3 software PBX products (costs & operating systems aside):

  1. Asterix ,
  2. Objectworld’s UC Server (, and
  3. 3CX Phone System (

PBX #2 and #3 both list compatibility with the SIP Gateways and make no mention to the interface cards. So if I were to invest in purchasing one SIP Gateway to test all 3 of these products, would the SIP Gateway also work with Asterix? How about the other way around?

If I’m not making sense or am confusing myself, please feel free to let me know up front.


yes you are correct you need one FXO port for every phone LINE you want to use with *

a sip gateway is very much like an ATA (analog telephony adapter)- it communicates with its server over Ethernet using the standard SIP protocol. As such it is the same as any IP phone or VoIP service, just a SIP peer. You can use it instead of an analog interface card if you want.
an ATA is a little 1-2 port analog to SIP adapter, the same thing like Vonage ships you when you sign up.

Asterisk speaks sip, and has been successfully used with a wide range of VoIP phones, VoIP service providers, and yes, VoIP gateways.

So in short, any SIP gateway device will work fine with *

Thanks for the reply IronHelix. Much appreciated and helpful.