Voip vs. PRI

Discussion in '3CX Phone System - General' started by Bsealey, Apr 15, 2008.

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  1. Bsealey

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    A portion of our company (10 employees) is moving to another location (to a building about 200 feet away) and I am considering a 3CX phone system exclusivly for them. They would still use our data network. I see that there are huge cost savings if the 3CX uses a voip provider like Broadvoice. From what i have read, this is risky in that you have to have a lot of control over the available bandwidth to the internet. In other words, if 7 people are on the phone using Broadvoice, and someone decides to download a 4 gig file from a bit torrent (which opens 8 connections) to the interenet, we will have problems. Am i correct? But if i go with 3CX and get a seperate PRI to it with 23 channels, they will not see these challenges becasue each call has its own channel. Have you all had success with Broadvoice or other Voip providers? What have you done on your local network to ensure good quality phone connections?

    Thanks

    Ben
     
  2. Arnaud

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    Hi Ben,
    bringing a T1 PRI in would indeed give you the garanteed bandwidth for each voice channel. Depending on the codec used you would however waist some bandwidth. You might want to look at the implementation of quality of service instead. Your ISP would need to support this as well though. What's the bandwidth of the internet connection for the new site you have have (in mind) ?
    Regards,
    Arnaud
     
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  3. h2009

    h2009 Member

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    Hi there,
    Depending on your budget, in instead of a PRI, you could always have a seperate broadband line for voice only.
    Just create a VLAN with QoS and you should find it no problem.
    Im not sure if you based in the UK or not, but there are alot of companys which are now offering voice only broadband lines which have great QoS to ensure that your voice calls are not effected.
     
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  4. Bsealey

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    Thank you for your time in the replies. I am based in the US. That is a great idea on the broadband for the voip. The only thing i see being a problem is the reliability. Is it possible to have both VOIP and PSTN lines into one 3CX. Basically ensuring that if the broadband goes down that there are still a couple of lines.

    right now the set up is: 1 PRI to our NEC aspire system. So thats 23 lines for 40 people in the building. We have two T1 lines for data. I want to use this oppertunity to move to an IP-PBX instead of the traditional.

    QoS needs to be provided by the ISP as well as by my firewall and my switches, correct?
     
  5. h2009

    h2009 Member

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    Hi there,
    Sure you can have as many PSTN lines as you want. The good thing abour PSTN line is that even if there is a power cut, the system will still work, where as with broadband unless your ISP can maintain your service at its local disto box you could be in trouble (not to forget UPS at your offices to run the networking equipment/phones)

    Personally if i had the choice i'd go for two different types of broadband- i.e. in the UK we have ADSL and Cable.
    Almost never (if ever!) have both gone down at the same time. Plus both can support high amounts of voice calls - remember you need a symmetrical throughput (2mb up/ 2mb down) for best quality.

    Here is an example of what can bought from the UK - http://gradwell.com/broadband/dslpremium/ and http://www.voiceflex.com/products/#vxdsl
    But being in the US im sure you have better solutions than us.

    QoS is needed from both ISP and local network - You should find that the cost of the setup is fairly expensive but the running costs are very low. And make sure you stress test the network whilst maintain a VOIP call to ensure the quailty isn't affected.
     
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  6. mickmarrs

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    Unless the company providing your IP access is also the company is providing your VoIP/SIP Trunk I would advise against going with a SIP Trunk. The $ savings for your company doesn't significantly outweight the configuration hassles and ongoing service issues. SIP trunking is not really prime time for organizations that depend on rock solid phone service. Then again if phone calls are not a main method of communication then a SIP trunk may suffice as long as you educate the users and the people paying the bills that there are issues. Then again there are issues with cell phones but the users were educated to lower their expectations.
     
  7. Halea

    Halea New Member

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    Bsealey:
    If the distance between your base and the new building where the team of 10 will be relocated is only 200 feet, you might want to simply use a high speed LAN bridge. It could be done with a top notch 802.11n type wireless networking access points installed at each location. These APs would bridge your wired LANs at your two locations. Your expense will be non-recurring, just one time. This is for your network infrastructure needs.
    As for your phone needs, if you already have a VOIP-PBX at your current location, you could simply put VOIP phone extensions at your new building. 10 additional circuits could be accomodated easily over the bridge in excellent conditions and leave many tens of megabits per second of additional bandwidth to accomodate your internet traffic. I doubt that you internet ISP link is going to be anything larger than 10 or 15 Mbps.
    Of course you will configure a VLAN for your VOIP devices just to prioritized their traffic, but you would do that no matter what ;) on your LAN with or without a bridge.
    My suggestion to you is to try this solution first and decide if it satisfies your needs. You could always bring in additional bandwidth.
    The idea of installing a separate PBX is not necessarily the best ideas of all if indeed 200 feet away you have your headquarters with full blown telecom infrastructure.
    The scenario that I am describing to you is something that I deployed in my own work place several years ago. We first used a laser bridge to interconnect two networks in two buildings located across each other with a 6 lane roadway in between (birds eye view 850 feet of distance). Our bandwith was only 20Mbps. It worked for many years, we only had problems when heavy rain occurred.
    Last year, we retired the aging equipment and installed 802.11n devices with directional high-gain yagi antennas. Worked beautifully, still does. Zero recurring charge. My budget-man loves it!
    Given the parameters that you stated, I suggest that you think out of the box and be creative. Otherwise, you will add up significant expenses to your budget.
    Cheers,
    Halea
     
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