What does a E1 / T1 VoIP card do?

Posted on 2009-02-14
Last Modified: 2013-12-27
Hi Experts,
  I currently use Asterisk as our phone system and was wonder what an PCI E1/T1 card did? I have seen them available (dont have one) so if somebody could explain to me in simple english what it is.. that would be great.

Question by:martinprint
    LVL 6

    Accepted Solution

    It would allow you to connect a T1 or Channelized T1 directly to your astrix box.  Channelized T1 was popular with dialup as it gave 23 to 24 dial in lines(depending on the provider for overhead) for a single T1.

    In your case, it sounds like if you wanted a dedicated T1, or ~1.5 up and down for VoIP you'd want to get your hands on one.  You would need a dedicated T1 for that box however.  Exception being unless you set it up as to masquerade (NAT) internal traffic as your router.

    Usually you'll have a cisco or juniper acting as your router and you connect your VoIP box behind that.
    LVL 6

    Expert Comment

    sorry, T1 being in the states, E1 being in Europe.
    LVL 36

    Assisted Solution

    E1/T1 is an interface containing 24 (T1) or 30 (E1) channels. Channels can be combined as a data channel and this is typically what people mean when they say they have a 'T1 internet connection'. In this case the T1 line connects to a router.

    The other common use for T1 is for telephony and this is also commonly known as ISDN24 (T1), ISDN30 (E1) or PRI (Primary Rate ISDN).
    Its line 24 or 30 telephone lines combined into a single interface but it has lots of advantages such as :-
    * Smaller interface.
    * Digital so no issues with echo etc...
    * Supports DID. This is where you are allocated a group of telephone numbers and the number the person called when calling you is provided. This enables companies to have lots of extensions with people being able to call them directly.
    * Instant dialing as DTMF is used so when people dial a number it starts ringing straight away without having to wait for the pbx to play the DTMF tones.

    Author Closing Comment

    The exact simple to the point answer I was looking for. Thanks.

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