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Wireless Networks Thread, VOiP in Schools in Technical; I am investigating VOiP in schools and if its worth implementing this in a single site school. What are the ...
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    VOiP in Schools

    I am investigating VOiP in schools and if its worth implementing this in a single site school. What are the advantages and disadvantages to this? What steps should I take before arriving at a decision?

    Any help will be great and any schools that have VOiP will be great!

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    localzuk's Avatar
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    Do you mean internal VOIP (ie. replacing the existing phone system with a VOIP one) or external VOIP (ie. replacing the phone lines with VOIP)?

    We have an internal VOIP system here, and its main advantages have been reduced costs (I built our system using Asterisk, Freepbx and Grandstream handsets) and flexibility (you can stick a phone anywhere you have a network socket).

    I've not found an external VOIP provider who can give us as good a deal as we get for our analogue lines yet though.

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    Thanks, I was looking at but options but I am finding it hard to gain advantages of an external VOiP system...any ideas?

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    Quote Originally Posted by matthogan View Post
    Thanks, I was looking at but options but I am finding it hard to gain advantages of an external VOiP system...any ideas?
    One advantage of using voip for phone lines is that you can scale quickly and efficiently, and depending on your provider this scaling can be up or down.

    So, if you were to need double the lines, you can usually get that enabled within a day compared to analogue lines which require installations by phone companies etc...

    It also has the advantage over analogue lines (but not digital lines, such as ISDN) of being higher quality (as there is no conversion from analogue to digital).

    However, having said I can't find a company that does a decent deal, i've just found these guys - SIP Trunking - Telappliant Ltd.

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    We use external VoIP provider (IAX2 trunks). We've found that:

    They're cheaper than comparable digital/analogue phone line rental (we can have 20 concurrent incoming and as many concurrent outgoing as out net connection will support for £30 a month (I think) - compare that with ISDN30!)
    Can have multiple outbound carriers so can chase lowest cost calls. You can also load balance between trunks.
    Porting takes 1 day if you need to move between VoIP providers (rather than the 2 weeks for normal porting)

    Cheers

    Will

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    dhicks (15th March 2011)

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    Abaddon's Avatar
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    We use a Splicecom system here, with a mixture of desktop handsets and softphones on laptops etc. Main advantage to me at least, is that every network port can be used for a phone, and as we have wireless everywhere, the softphones on laptops are very handy.

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    Quote Originally Posted by Willott View Post
    We use external VoIP provider (IAX2 trunks). We've found that:

    They're cheaper than comparable digital/analogue phone line rental (we can have 20 concurrent incoming and as many concurrent outgoing as out net connection will support for £30 a month (I think) - compare that with ISDN30!)
    Can have multiple outbound carriers so can chase lowest cost calls. You can also load balance between trunks.
    Porting takes 1 day if you need to move between VoIP providers (rather than the 2 weeks for normal porting)

    Cheers

    Will
    Can you tell us who you're with for that?

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    Yep, it's Gradwell | Enterprise VoIP | SIP calls | Sip Trunk - SIP

    It says £4 per number (2 concurrent calls), but they do discount for packages - we have 10 numbers (so 20 concurrent) for either £20 or £30 - they don't limit calls by number (so we can have all 20 going to one number and none going to any others)

    As for Gradwell, they're usually at the forefront of VoIP in the UK - their MD was part of the team that worked on 999 integration system for VoIP and they seem to be very hot on support - they've got a large cluster at each layer of their IAX2 and SIP platforms, and are continually developing their systems. I used them when doing business support previously and also had no issues.

    Cheers

    Will

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    Quote Originally Posted by localzuk View Post
    We have an internal VOIP system here, and its main advantages have been reduced costs (I built our system using Asterisk, Freepbx and Grandstream handsets) and flexibility (you can stick a phone anywhere you have a network socket).
    I've been looking in to VoIP systems, too. Our current analouge PBX is basically full, we can't add any more handsets around the school, and if we did we'd have to run more wiring anyway, therefore a VoIP system that works on CAT5 cabling would seem like a sensible option. To avoid having to install any more cabling at all, I understand many VoIP handsets will act as switches, letting you plug a classroom PC in to the same network connection as the handset and thus avoiding having to run any new cabling. However, we would also like to be able to power handsets via PoE, which would only give us a 100Mbps to each classroom machine rather than 1Gbps. Do most people think that would be an acceptable speed?

    As most handsets would probably be within reach of a power supply anyway, I was thinking we could buy gigabit switches and separate PoE midspans, then have PoE handsets deployed as needed, so most classrooms would end up with a gigabit connection but we'd still have PoE capability for wireless access points or any awkwardly-located handsets. This would need gigabit-capable handsets - are there such things available, does anyone know makes / model numbers? Am I correct in thinking that PoE only supports 100Mbps, or is there some (non-standard?) way to get around that?

    Building / buying an Asterisk server to interface with a number of existing analouge phone lines looks easy enough - you just need a rackmount case with motherboard, etc, and a Asterisk-compatible analouge phone line interface card. However, I'm not sure exactly what I'm looking for to plug that interface card in to - our current analouge PBX is 3 large beige boxes attached to a wall in the front office with a tangle of wires inside. I assume those analouge interface cards just plug in to a number of standard phone wall sockets, so if we have a dozen phone lines we're looking for a dozen wall-sockets to plug a dozen cables in to from our Asterisk server. Is it likely we'll need to get someone (possibly BT) to come in and install a bunch of wall sockets?

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    localzuk's Avatar
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    I've yet to find a need to upgrade workstations to 1Gbps connections, 100Mbps has always been fine. There are 1Gbps phones that support PoE though, such as this one - Siemens Gigaset DE700 IP Phone.

    To terminate your analogue lines, you will somewhere have BT sockets with normal phone connectors - the BT engineers I spoke to said that is always the case. So, yes, if you have 12 analogue lines you'd have 12 normal phone sockets.

    However, I'd suggest that with that number of lines, you should be looking at replacing them with ISDN or IAX/SIP over your net connection.

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    Quote Originally Posted by localzuk View Post
    There are 1Gbps phones that support PoE
    Many thanks, I'll investigate that a bit further.

    To terminate your analogue lines, you will somewhere have BT sockets with normal phone connectors - the BT engineers I spoke to said that is always the case. So, yes, if you have 12 analogue lines you'd have 12 normal phone sockets.
    They'll just be well-hidden - probably somewhere behind the custom-fitted, polished, solid-walnut cabinets in the front office...

    However, I'd suggest that with that number of lines, you should be looking at replacing them with ISDN or IAX/SIP over your net connection.
    How many lines do you have? You implied at the start of this thread that you were okay with the analouge lines you have - have those companies mentioned above changed your mind, or do we just have a larger amount of telephone lines?

    I was rather thinking to do any conversion to VoIP in easy stages. We could get an Asterisk server with an analouge interface card and plug it in to a single analouge phone line for testing. We have a backup ADSL line in our server cupboard, should there be any issues using that phone line with a VoIP system? Buying a 12-line capable Asterisk server might be slight overkill if we move to a SIP trunk in the future, but such an interface card is maybe £500, which is worth it if it means we don't have any outages while moving phone systems.

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    We have 3 lines going into our PBX, and one separate for our fax. I've always wanted to replace them with something better, but have never found a cost effective solution yet (analogue lines have more configuration required, involving gain levels etc... and it is a pain to get right).

    There shouldn't be any issues using your broadband enabled line as your test analogue phone line.

    Personally, I wouldn't buy interface cards. I'd instead buy a gateway device such as this - Vegastream Vega 50 Europa Gateway 8 x FXO.

    The reason being is that it is designed for the conversion part, and configuration is supported more easily than manually setting gain levels via an interface card. It also means that your phone server can be tiny, and not need expansion slots etc... - So you could do a picoATX system with CF as the storage space. Or just buy one of these sort of things - Rhino Ceros 1U Chassis, 2GB Flash Drive (CerosMini-2GB-ST)

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    Even a G.711 64kbs uncompressed codec wouldn't stress a 100Mbs connection. But where you have multiple lines going through the switches, then being able to prioritise VOIP traffic through the switch is essential. You won't run out of bandwidth but if latency rises, the call quality will tank. For the original poster, this is one area you MUST deal with before arriving at a decision.

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    Quote Originally Posted by pcstru View Post
    Even a G.711 64kbs uncompressed codec wouldn't stress a 100Mbs connection. But where you have multiple lines going through the switches, then being able to prioritise VOIP traffic through the switch is essential. You won't run out of bandwidth but if latency rises, the call quality will tank. For the original poster, this is one area you MUST deal with before arriving at a decision.
    Indeed. My suggestion for VOIP is a) make sure you have QoS enabled for it and b) if internal, subnet your network and put VOIP into its own VLAN.

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    How's you're current PBX supplied - from your description of 3 beige boxes with loads of wires, that sounds like 40 pair connection boxes or similar - this may be incoming BT cables, or linked to your PBX. Do the boxes have circuitry in or are they just wire to wire connections? What make is your current PBX, are there any digital handsets?

    It was issues like that that made me stay away from any analogue in my system. Made the jump from analogue/digital phones with 2 ISDN2e's for incoming calls straight to full IP. Interface cards and location of incoming lines were going to cause me issues - my PBX is fully virtualised running as a guest on Xenserver on our virtualisation cluster in the server room - high capacity connections direct to core network. I compiled asterisk to ensure there were no timing issues, but I think that things like PBXinaflash have sorted these issues (as they quite happily run as virtual machines).

    As far as incoming lines, I'd suggest the following:

    Have 2 numbers setup on your incoming VoIP provider, have 2 trunks, one aimed at your one of your main net connection external IPs, one at your adsl backup IP, setup your main number to go to your main net connection trunk, with a failover to the second number if it can't connect. The second number is targetted at the adsl trunk with failover to an analogue line, connected to a single analogue phone in reception, theory being, if can't connect to main, net connection may be down, so try secondary, if can't connect to secondary, it's most likely that PBX is down, so fallback to old tech!

    For outbound, normal routing would take care of connection failure.

    The only line we don't currently run over our PBX is the fax line - this was never on the old PBX and I'm still awaiting full T.38 support from Gradwell, and finding a way to do fax to email for confidential stuff before I try to implement it again (ie either multiple fax ready numbers or extensions or something) and something for fax to email as well - though that should be less difficult.

    Cheers

    Will
    Last edited by Willott; 15th March 2011 at 01:48 PM. Reason: info about fax

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