VOIP "PABX" Questions

[cpvh]

Further to my earlier post regarding Coolports. I have checked with my friend, and found that the Telephone Handsets aren't digital phones, but VOIP handsets.

Am I right in thinking that in terms of cabling these are just Ethernet Twisted Pair devices which usthe same two pairs as 10 Base T or 100 Base T and could therefore be expected to work with the 2 x Data type Coolports (Or more to the point the cheaper (though less sexy) port economisers which Videk and others stock)?

I can probably get away with just using these devices on the computer connections (where I know there will be no problems), but it would be interesting to know if they could also be used with the VOIP kit.

[Sparks]

If they are just VOIP phones, then yes - you can even get a small Ethernet hub/switch and split 1 port to as many as you like. Like this @ £13.44 for example

do require power though, so you need a spare socket near by.

They also seem to do a two port passive version (meaning no additional power is required)

is only £4 First passive network hub I have seen though, so I would check if it really is the case!

If you do use a hub or switch, then the maximum data throughput will be 100 megabits, rather then the 200 megabits if you split the cable, so if there is a PC with heavy network use in the equations, then I would want to split rather than using a hub. If it was a couple of phones or a printer and a phone, then a hub should be fine.

Some VOIP phones also have another Ethernet port on the back to plug other stuff into, so it is worth looking at the back first (but sometimes this can only be a 10 meg port)

Sparks...

[cpvh]

Thanks for that Sparks,

I am trying to avoid using hubs for the reasons you suggest. The "client" has had problems with slow network connections where they have used downstream hubs before (though perhaps they were cheap hubs).

Are VOIP "Phones" generally 100Mb/s devices? If so, I presume this refers to 100Mb/s full duplex? If so (what a lot of if so's) where does the restriction come in? If you have say Device 1 - Switch - Switch - Device 2 all on 100Mb/s Full Duplex where is the restriction? Or were you thinking that if there are 2 devices at 1 end, then by sharing the first switch, they get less than 200Mb's each? I suspect you know that the degredation even with 10 devices would (or perhaps I should say should) be less than that, so I think it must be something else you have in mind.

Yours enquireingly

Chris

[Ian Stirling]

The 10 meg port is only a problem if you connect other devices to it. You'll 'never' run out of bandwidth if you just connect phones.

VOIP phones will use at most 30K/second or so, so 10 of them on 10mbit is not a problem. If you're really concerned, an extra 5 quid or so on a switch, rather than a hub will utterly eliminate the problem, and let you run thousands of phones on a 100mbit wire.

[Owain]

Yes, but check whether they use Power Over Ethernet which might need an extra pair?

Owain