Why PRI not BRI ?

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Asterisk Users 3 Comments

Hi List,

I have stupid question but I want to know it. Why we use the PRI insted of
BRI ? Just for the sake of number of lines or any thing else ?
And why SIP is used for making calls rather then IAX? Even we know IAX takes
1 channel for making calls?

3 thoughts on - Why PRI not BRI ?

  • Sunday, May 29, 2011, 10:57:00 AM, virendra wrote:

    Yes, because of much more channels. But if you need only 2 or 4
    channels BRI is cheaper. From 10-12 channels becomes PRI cheaper.

    And the other reason: if you use traditional channel banks instead of
    VoIP phones that uses PRI also.

    Maybe because of almost every VoIP phones knows SIP. I personally
    didn’t meet any IAX VoIP phone.

  • It probably depends on your country.

    In mainland europe (or maybe just Germany), ISDN2e (BRI) is very popular –
    not uncommon in home installations too.

    In the UK, it’s almost the standard in small businesses – the migration
    path seems to be from a single line to 3 lines sharing the same number to

    There was a push in the UK to support BRI in the home (~10 years back,
    under the name Home Highway), but it came at a time when ADSL was almost
    upon us, and BT in their infinite wisdom removed a lot of the ISDN
    features that make it actually useful…

    I don’t think BRI ever caught on in the US – It was analogue or PRI (or
    channelised/fractional T1 or whatever it’s called) Probably made it much
    easier for the telcos to support (and afford)

    SIP is an open standard that’s been around since the late 90’s. IAX, which
    is also open and free was only just accepted as a standard last year, but
    even so, there’s inertia. Very few phone manufacturers are using it – why
    should they, when they’ve been using SIP for years, and the same PBX that
    works with IAX also works with SIP… (And does any other PBX support IAX


  • Only reason for using bri instead of pri in the number of voice chanels
    and costs. It took ages before telco’s realised that with fractured-E1
    they could save a lot of costs (telco/customers) while offering a cheap
    upgrade path. At that time that ISDN was introduced, the costs in
    installing a pri-interface in the local-exchange was identical to
    installing a bri-interface.

    Only reason nowadays for using bri instead of pots, is that you get the
    incoming speech channel already digitialised.

    Freepbx is the only other afaicr.
    Only a limited number of clients.