The cheapest way to do VoIP is still analog

The cheapest way to do VoIP is still analog

Summary: What happens when you want to just want a bunch of phones in your business, hotel, or organization and you don't need a bunch of fancy and complicated features on the phone?  It's simple, just get a bunch of cheap analog phones.


What happens when you want to just want a bunch of phones in your business, hotel, or organization and you don't need a bunch of fancy and complicated features on the phone?  It's simple, just get a bunch of cheap analog phones.  But how do you build a phone system to support a bunch of analog phones?  It's simple, just get a PBX (Private Branch Exchange) with a few FXS interfaces to plug in the phones.  Just to rehash what an FXO and FXS phone port is and what the differences are, here's a text representation how these devices are connected:

  • Phone (FXO) - (FXS) Channel bank (FXO) - (FXS) Telco
  • Phone (FXO) - (FXS) Telco

But this is where the tricky part comes in since your typical IP PBX which is essentially a computer doesn't have any FXS interfaces so that's where channel banks come in.  A channel bank traditionally converts a T1 PRI interface in to 24 separate channels for 24 phone lines.  The problem with traditional channel bank is not that they're all that expensive, but the fact that they require a T1 PRI interface on the PBX for every 24 phone lines which are very expensive and cumbersome.

To get around this problem of having to use expensive T1 cards that are tied to a single server, Xorcom shuns T1 cards and uses good old USB 2.0 for its interface to the PC.  Pictured below are some Astribank products with FXO or FXS ports along with the option for PRI ports.  You just plug in your TBX to one of the Astribanks via one of the abundant USB 2.0 ports and you're done.  Simply plug it in to a USB 2.0 switch and two cheap open-source PBX appliances and you can instantly flip between the two servers in case one of them goes down for whatever reason.  Any problems with one PBX server and you simply need to flip the USB switch and the other PBX is instantly lit up with all of its FXO and FXS ports.  Trying to swap a PCI card with a T1 interface is far more difficult.

Pictured above is the front view of three Xorcom Astribank models ranging from 8 to 32 ports with any mixture of FXO and FXS ports.  Pictured below is the back of the units showing the power and USB port in the back.  The larger models also have 50 pin breakout ports so you can use your existing breakout box if you chose to do it that way.

The next two photos show all-in-one appliances designed to run Asterisk or Asterisk distributions from popular vendors like Trixbox or some other Asterisk derivative.

Topics: Unified Comms, Hardware, Mobility, Networking, Telcos

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.


Log in or register to join the discussion
  • Very interesting!

    But these are probably more than I need at home. (kidding)

    Thanks George for a good topic!
    D T Schmitz
    • Not unless you need 8 analog phone ports :)

  • Just a minor nit - otherwise, great job!

    Just a minor nit, George:

    "A channel bank traditionally converts a T1 PRI interface in to 24 separate channels for 24 phone lines. The problem with traditional channel bank is not that they???re all that expensive, but the fact that they require a T1 PRI interface on the PBX for every 24 phone lines which are very expensive and cumbersome."

    A T1 PRI can only support 23 voice channels, not 24. A standard non-ISDN T1 can, though. Consequence of common-channel signaling versus the old channel-associated signaling.

    And if you went to the trouble to define what PBX stands for, some readers without Newton's Telecom Dictionary may be scratching their heads over FXS (foreign exchange station) and FXO (foreign exchange office). :)

    But seriously, Xorcom's products here show the sheer utility of the "Universal" Serial Bus - a dozen years ago, who would have had the foresight to predict what interface it would supplant, and what mini-industries it would spawn? All from some "lowly" PC interface!
    • TLAs

      Thanks for the definitions of FXO and FXS. It made the previously non-sensical explanatory diagram into something useful.

      I think I can live with terms like "JAVA", "AJAX", and "Wi-Fi", but less common TLAs (three letter acronyms) ought to be defined when first referenced unless you're only writing to those who already know what you're writing about.
    • Good points

      That "lowly" PC interface version 1.0 operates at 12 Mbps versus 1.554 Mbps on a T1. Xorcom uses the USB 2.0 interface which operates at 480 Mbps with sustainable rates of 240 Mbps.
  • Wiring

    The problem with splitting out to analog is all the wiring punch down that has to be done. Being able to use an IP phone on any local network connection along with the ability to add more connections by simply adding workgroup switches makes internal wiring so much easier.

    In many cases the cost of wiring is equal to the cost of a good IP phone. Plus, with an IP phone moves are so much easier.
    • Per port cost

      What is the per port cost of that equipment? I doubt it is less than a 10/100 Ethernet port.

      Need to setup a small call center on the other side of the building? All you need is a single network connection as opposed to a dozen or two wiring pairs for analog.
      • Small works for IP.

        I agree that small applications, like a new branch office, make VoIP a perfect fit. But...

        You should have heard me laughing at the Cisco rep who tried selling me a $300,000 VoIP system for my 120 phone headquarters office.

        We went with a Mitel IP conversion that allowed us to keep all of our analog phones and still have IP connectivity to our new VoIP branch offices. $23,000 for the Headquarters setup and $10,000 per branch.
        Hates Idiots
        • Every situation has its own cost/benefit

          Yeah, Cisco is nuts. I know that laugh.

          It all comes down to what pieces you are adding or changing -- trunks, pbx, phones. In your case it looks like VOIP made sense for connecting your remote locations. For us, it made sense internally and between our two local locations.
          • Cisco, Nortel, Avaya, they're all expensive

            You're looking at $250 to $350 for the phone and you can double that by the time you include the cost of the PBX. Then Cisco wants even more money for those gigabit ports with PoE which they'll upsell you at every opertunity. They just love selling those quarter million dollar Cisco CAT6xxx switches.
          • Not a fair comparison

            George's story talks about an open source Asterisk/FreePBX call server. Comparing to Cisco Call Manager at list is not reasonable. The cost of the FXS ports compared to an IP phone on the same call server is close.

            In fact Cisco 2941G's that work great with Asterisk/FreePBX are only $200.00. Many inexpensive, managed PoE switches are on the market.

            If somebody at Cisco is selling you a 6000 series switch for desktop ports then you need a new reseller.

            And $120k for is crazy. Just had a customer with 450 phones, 100 seats of advanced call manager and IP Unity go out the door configured for $250k.

            Our favorite sell though is Cisco phones on Asterisk/FreePBX, an extreme bargain.
      • Wiring could be CAT-5 or 2-pair for the analog phone

        Wiring could be CAT-5 or 2-pair for the analog phone. But the real cost isn't the cost of the IP phone, but the cost of managing the firmware on the phone and dealing with the security issues. Until IP phones start offering something compelling like wideband support (not just codec but having good enough speakers and microphones), I don't see why I would want one.
      • That's a separate case

        These devices target a very specific problem, i.e. using analog phones with a IP based PBX without T1/PRI interfaces attached.
        So, when setting up a call center the scenario changes significantly and other solutions exist for that purpose.
        So, these devices provide with an elegant solution to a classical problem.
  • My solution

    My solution: Skype plus a few Skype-aware cordless handsets. Some even have WiFi, and can be used anywhere in a hotspot.
    • Ya tht is cheap

      Look at my name I'm scottish and that skype solution is cheapest by far but It's not a pbx. How would you get company annoucement? Automated operator?
  • Major Issues with VoIP deployments

    What is typically missing from cost-benefit analysis of VoIP implementations is the requirement for backup power... not only does the supporting network require this, but do to the phones themselves. Providers of networking services that support VoIP may or may not provide continuity-of-service during power interruptions... and while it is common to have a data center on backup power, it is less common to have an entire network on backup power.

    Also, 911 services need to be routed/programmed correctly... in an implementation between branch buildings within Seattle, a non-profit failed to take these things into account... and had to install at least 1 analog phone line per building to support emergency communication needs...
    • That's not all.

      It can play hell with credit card machines, fax machines, and any other machine that uses a standard modem for connections. If your VoIP doesn't use channels of at least 9.6kbps (many use 4.8), those faxes and credit cards aren't going through.
      Dr. John
    • Power concerns are legit, but manageable.

      We deployed Mitel 3300 IP PBX's to 4 remote offices and power for the phones was a big concern. With between 10 and 24 IPphones per locations we went with HP 2600 series ProCurve PoE switches. Being a service-oriented non-profit we already had our LAN on UPS?s in each office. We just upgraded them to APC 2200?s, as they needed to be replaced in the 18 months before the VoIP project began.

      That spread some of the project cost out over 2 budget years and has given us over 4 hours of run time for our IP phones, LAN switch, router, AD file server and Mitel box. This was proven in our second largest branch when they at least had usable phones for a 4 ? hour power outage.

      As a backup in case of a PoE switch failure we have a standard 48-port Cisco switch we removed from an office while upgrading to the PoE switches. To provide power for the IP phones we have inline power adapters that go on the phones LAN cables. It was far cheaper than buying another PoE switch to sit on a shelf.

      We are not worried about not having a spare PoE switch. If a severe spike frying the PoE switch preceded an extended power outage it likely fired other equipment and the office will be closed until everything is repaired.
      Hates Idiots
    • It's easier to power dumb analog phones

      It's easier to power dumb analog phones; they take far less power and they get their power from the channel bank. Battery backup of a channel bank is far easier than backing up a big 802.3af PoE switch; we're talking maybe 4x lower power.
      • Re:It's easier to power dumb analog phones.

        Most things are easier with analog phones. They are the only ones that can ALLWAYS be adapted. They also co-exist quite happily with a 9600bps modem, as used for fax or bank terminals.