To VOIP or not to VOIP, that is the question

[localzuk]

Hello everyone, first time poster here...

I am the ICT Manager/Technician at a school in Somerset where we are looking at replacing our existing phone system. We currently have a digital PBX and standard digital phones but we have outgrown its capabilities.

So, we have a few options: get another similar system installed with the extra functionality at considerable cost or do it in house using off the shelf or open source VOIP equipment for a much lower cost but increased work for myself (which, I must admit won't be a major problem).

Has anyone had any experience of implementing a VOIP system in their school? Am I taking too much on thinking of doing this?

Some details of what we have and what we want:

Have: 20 extensions - nothing fancy, call transfer, conferencing etc... 3 analogue PSTN lines in the system and 1 for a fax line

Want: 30 - 50 extensions, some wireless/dect - with 2 way radio functionality to remove the need for a seperate radio system, voice mail for each member of staff (with option of sending it to email inbox), phone to phone messaging (ie similar to SMS) to reduce the need for 'runners' with messages from the office, a on computer interface for the receptionist (dragging and dropping of calls, sending of messages etc...). Plus the standard stuff such as conference calls.

I have already set up an Asterisk server and a couple of software SIP clients to test it out and see how difficult it would be to setup/manage and I am liking it. I am in the process of buying a couple of cheap hardward SIP phones to try out also.

One of the key areas that we have to consider, as far as I can see, is QoS on our switches (which are all too old to support it but are due for replacment next year anyway). Has anyone got any ideas about this side of things?

I look forward to your responses!

[CyberNerd]

One of the key areas that we have to consider, as far as I can see, is QoS on our switches (which are all too old to support it but are due for replacment next year anyway). Has anyone got any ideas about this side of things?

You should get this side sorted first, some decent managed (layer3) switches and use vlans. You don't want the phone system out of action if there is a network error/virus/DoS. Better to segregate the phone system entirely rather than rely on QoS.

[localzuk]

Hmm... I shall have to go back to my uni notes and read up on vlans a little more. I understand their usage to prevent broadcast storms by segregation, but how does it apply to this sort of set up? Can you dedicate bandwidth by vlan?

Also, we currently use Dlink network gear, and I am keen on moving to HP stuff. What do other people use?

[plexer]

well a vlan is just that a virtual lan so you can use one to confine all of your voip to their own virtual lan which means you won't have a qos problem when voip traffic would otherwise be fighting with data traffic to arrive in the correct order.

Ben

[CyberNerd]

I understand their usage to prevent broadcast storms by segregation, but how does it apply to this sort of set up?

If the network is segregated to smaller broadcast domains the effect is to increase bandwidth for that vlan, the voip network is 'protected' as it is isolated from the computer network on the other vlan. I suppose you are dedicating bandwidth because (when not using frame tagging) each vlan has its own uplink - my understanding is that if vlan 1 becomes saturated, vlan2 isn't affected - hopefully someone can clarify this.

[Ric_]

@localzuk: What is your existing phone system? We currently have an Avaya IPOffice (a digital system, despite the name) but since the upgrade to IPOffice v3, it now supports IP handsets too.

As we add additional extensions in the future, I intend to use IP phones instead of digital ones. admittedly th phones are more expensive but the cabling costs are reduced since existing (or easily added) Cat-5e can be used.

You seem to have a good idea of what you are ultimately after so I think it is more of a process of finding prospective systems. I would also make sure you have a comprehensive maintenance cover on the system. Telephones are your school's link with the outside world and you cannot afford to be without a phone system for more than an hour or two at the most.

From experience, I would also recommend you review the number of lines that you have. If you increase from 20 to 40 (for examlple) extensions, the demand for concurrent calls is bound to increase. We have 3 ISDN lines (i.e. 6 lines) and that regularly fills up with 20-30 extensions.

[ChrisH]

We have 3 ISDN lines (i.e. 6 lines) and that regularly fills up with 20-30 extensions.

.... and one of those lines is guaranteed to be busy if Ric is in work

[john]

Have you guys never head of Skype or MSN, think of the cost to the school! and if your lines are getting full don't forget ISDN30 may be the next step up.

As for phone systems, I saw a nice Cisco one the other day, looked very shiney! but having room to upgrade is what you need

[Ric_]

@john: You cannot tell us to use Skype/MSN to chat and then tell us to get a Cisco phone system - the cost of Cisco far outweighs any savings!

Besides... no Skype or MSN possible here

Something that would be interesting to look into is the IP routing services of the Avaya system... it can route calls via Internet services for lower call costs. It will also make its own mind up as to which route is cheapest.

[Geoff]

If you want to go the open source VOIP route you need to be looking at Asterisk.

http://www.asterisk.org/

You should probably start off with a premade liveCD.

http://www.automated.it/asterisk/
or
http://www.trixbox.org/

and some software IP phones.

http://www.voip-info.org/wiki/index....nes#SoftPhones

[budgester]

If you want a supported Linux VOIP platform with hardware etc.

You could try http://www.splicecom.com/

We have it installed here, with around 100 extensions, and they have just added SIP trunk support.

If you really want to get flashy check out the PC400's think electronic registration with these puppys.