Newbie Questions

I’d like to setup my SOHO for 3 phones. What services from the phone company do I need for the 2 questions below? I’m more interested in what I need to ask the phone company (lionshare of cost I would presume) - I can hack on the local side later.

1. 3 local extensions accessible from outside
I’m presuming Direct Inward Dial is what I want. Is this correct? In term of hardware need a card that has 1 - 3 fxo’s? I believe the phone company provides the extension number that Asterisk can use to route to extensions.

2. 1 external phone number 3 local phones.
No Idea what I’d ask the phone company. Does this mean I need a 3fxo connection card and have the phone company bind 1 phone number to the 3 fxo’s? I guess my question is what do I ask the phone company to map 1 phone number to 3 fxo’s so that Asterisk can determine where to route calls.

Any information greatly appreciated,


You have a number of different ways that you could proceed. First of all you don’t need a separate telephone line per IP telephone but you will need an FXO connection per telephone line. You don’t need any direct telephone lines at all if you don’t want to. You can get the numbers delivered via a SIP service provider via a SIP trunk directly into the Asterisk system (assuming you have an Internet connection that can be used for this).

DID numbers would be required via a SIP trunk if you wanted a direct dial number per phone. However if you are happy with one number for all phones you can have Asterisk ring all of them when one number is dialed or hunt around them ringing them one at a time. Asterisk can even ring all of the desk phones and then call an external extension if no one answers these (or divert to voicemail).

There are so many options it’s difficult to cover them all here. Suffice to you that if you want analogue telephone lines you need an interface card like the Digium TDM400. For a SIP trunk on additional hardware is needed.