1000 Analogue Lines With Asterisk

Home » Asterisk Users » 1000 Analogue Lines With Asterisk
Asterisk Users 15 Comments

Hello all, Can someone recommend what hardware to use for a 1000 analogue line capacity asterisk PABX?

Regards

15 thoughts on - 1000 Analogue Lines With Asterisk

  • Hi,

    For analog, I really like telco grade channel banks.

    I would recommend the adit 600, there is a good market on Ebay, and you can do 48 channels per adit 600, with 2 T1 interfaces. Having onsite spares would not be an issue (cost is low). You can put two next to each other in a rack, taking up about 2U of space per 2 channel banks.

    You could service this with six eight port T1 cards, or with eleven/twelve quad T1 cards. I would distribute across two, three, or even four servers for redundancy/resiliency and load balancing.

    -Harry

  • There is definitely no way you should put 1000 lines on a single box. To be honest I do wonder what you want to do with 1000 lines as your description probably changes the recommendations.

    Kind regards,

    Matt

  • Thanks

    When I designed the server, I catered for only IP phones but customer want to discard the existing analogue pbx while they want to reuse their cables and analogue phones.

    Regards

  • A PCI express card with four primary rate ISDN ports, each linked up to a channel bank, will give you 120 analogue lines. So you will need nine such cards; and for reasons of simple numbers of slots on a motherboard, they will have to be split among three or more servers, linked to a gigabit switch.

    You might end up getting a better deal if you bought 1000 hardware SIP phones.
    (You also would probably increase your personal indispensability factor, into the bargain …..)

  • +1

    spending money to get that many fxs ports is going to negate any savings of reusing analog phones instead of buying ip phones

    1000 analog ports sounds like hell and if it was me I would be embarrassed to have a setup like that tied to my name if I was a consultant etc. Someone will come in after you and ask who set it up and the customer will say you 🙂

  • That would be the expensive route. The inexpensive route would be to buy FXS ethernet gateways, like this:
    http://www.voipsupply.com/grandstream-gxw4248. You could then get by with a single reasonably sized asterisk box (probably two setup as HA)
    and no need for expensive cards or complex channel bank setup. We have done many hotels this way with great results.

    j

  • Hi,

    All of the back and forth of Analog vs VoIP handsets tend to ignore some of the basic issues.

    What type of cabling is in place, does it need to be upgraded to do Ethernet, etc.

    The “gateways” can be handy if there are many closets where the wiring terminates AND you have Ethernet to these locations. That being said you probably should have some amount of backup battery power any location you put a gateway. You can also do this running your own T1
    lines to the closet and channel banks in the closet.

    If all of the lines come back to the same place, you only have to have backup battery in a single location.

    I have seen enough hackish VoIP deployments, that I can see many cases that Analog is cleaner. For example, IBM Type1 cabling, can’t run PoE, so they installed wall warts with each phone…

    You also have to look at the use case. Doing an “office” with Analog is very different then doing a phone in each classroom at a school, or even hotel phones.

    The channel banks, even if you have to buy multiple to get the right cards, should average under $200 each, 8 port T1 cards are about $2K
    each, total cost to service 22x$200 + 6x$1000 = $10,400, or about $10
    per port, and you should be able to do it cheaper then this. This is of course using Ebay pricing, new would be much higher.

    The gateways run about $25-30 per port, even for the lower end (like the Grandstream below).

    Cabling costs depend greatly on location, around here it averages
    $100/drop in office environments, if your only doing one run to each room, it gets even higher, this is where the real cost of using VoIP
    handsets comes into play.

    -Harry

  • What about leaving the old PBX in place and trunking it via ISDN to the asterisk server.

    We use rhino 24 channel bank but are 2U for rhino + 1U for patch panel.
    (RJ21 cable so might be able to use existing ones if they are RJ21)

    Used USB xorcoms a while back, things may of changed but if one is down and reboot server then asterisk doesn’t come up.

  • Not with recent versions of DAHDI. Assuming you set auto_assign_spans=0, DAHDI channel and span numbers are mapped in
    /etc/dahdi/assigned-spans.conf the order of their startup is irrelevant:
    the identification of channels attached to either serial number or connector, and not to semi-random initialization order.

    And this is why Asterisk could afford itself not to fail if DAHDI
    channels are missing. Originally it failed because missing devices meant that a device may be missing and thus existing channels may be misplaced.

    With a recent enough version of Asterisk, and with ignore_failed_channels = true in chan_dahdi.conf (the default as of 13. Makes sense also if you only have a single DAHDI device to begin with)
    Asterisk will not fail if channels are missing: they wil just come later. And indeed Asterisk can now allow DAHDI channels to be created after initialization, and thus Asterisk does not need to wait for all DAHDI devices to initialize before starting.

    (This is not specific to Xorcom hardware and should generally apply to any DAHDI hardware. I’m not exactly sure how this interacts with dynamic spans and interested to hear reports, probably in a different thread)