Does anyone know if there’s any way to get voice over ATM (voice over DSL) working with asterisk? I’ve done a bit of searching, but haven’t come up with anything concrete.


I’m looking for anything on VoDSL too. Otherwise I have to pay more for an extra provider and I wanted to prevent that from happening :smile:

DSL or ADSL are just transport systems to allow fast data over the copper phone line between you and the telephone company, they go no futher.

The data that’s actually being transported is generally TCP/IP or UDP/IP (plus a few other /IPs) - in other words, it’s all IP (Internet Protocol), so what it comes back to is Voice over IP.

The commonest connection type is Ethernet, so you need an ethernet-connected ADSL Modem/Router box and you can then plug in an Asterisk machine, any other Ethernet VoIP devices like ATAs or Hardphones, plus your existing PCs which can then use the internet connection and also run a softphone on the PC if you wish.

If you already have ADSL on a USB-connected modem, you can generally replace this with an Ethernet-connected ADSL box so you can use the same internet connection for data and VoIP.
If you are going to do this, make sure the ADSL modem/router supports Quality of Service (QoS), so the voice quality is not messed up or interrupted by other internet use.


do you have any experience with Asterisk and VoDSL. The information I got from my provider was explicitely VoDSL not VoIP. I do not want to sign a new contract and find out later that I can’t use the services because I need different hardware.

EDIT: I want to implement a Debian router with Asterisk to provide telephony for my studentflat. So this is covered.

Thanks in advance.


The telephone company so-called VoDSL seems to be (in principle) an ADSL modem with built-in FXO ports, similar to many available ADSL + VoIP boxes.

The diffference in function appears to be that these are dedicated units used by telephone companies to provide extra ‘lines’ at a customer site without the cost of installing extra cables (as they use some of the ADSL bandwidth to carry the extra voice traffic).

Basically a newer, faster version of the basic ISDN line & box that provided two voice lines over one copper cable.

Either way, the xDSL side is strictly a method of providing fast data over copper phone lines and does not go beyond the telephone company exchange.

At the exchange end, an ADSL line is connected to a DSLAM which does more or less the same as your ADSL filter and modem - the basic phone line goes into the standard exchange and the high-speed digital signal is demodulated and the data routed through their internet trunk.

At THIS point, the telephone company could intercept the signal and do what they liked with it, such as using their own data standard to link through to the extra phone sockets on the box at your end - but for anyone other that the phone company, the only way I can see to get anything past the exchange and to the rest of the world is to use the internet.


this means basicly the support girl is just repeating the stuff she learned in a two hour training and I am able to set up Asteris with this “VoDSL” line without any trouble…!?

Will try it next month when I’m able to change the contract. Will post the stuff I found out here :smile:

Thanks for your help.


In VoATM scenario voice is transferred over the ATM (over DSL) link directly, without IP as we have it with SIP telephony. Regular codecs like G.711, G.726 etc are used.
Customer is usually provided with the IAD which is talking ELCP (Emulated Loop Control Protocol) with the provider’s box (IWF, InterWorking Facility). IAD is providing the customer the regular FXS ports, so analog card will be required in Asterisk.


this makes sense. So basicly I have to use an analog card in my asterisk to backlink to my appliance so I could use the VoATM signal.

Damn dutch providers. VoIP is so nice but noooooo!