[kwlug-disc] VoIP Question.

John Van Ostrand john at netdirect.ca
Tue Feb 8 13:26:04 EST 2011

----- Original Message -----
> So.... I think I am slowly getting this VoIP thing.
> I just have a question about a scenario..
> Scenario: We have an employee who will be in Cosat Rica in a couple of
> weeks : permanently.
> Requirements:
> We want to give him a Cambridge number. Toronto if Cambridge can't be
> done.
> We want him to be able to call POTS all over the world as cheap as
> possible, or unlimited plan of some sort if available.
> We dont need him to interface with our current office phone system.
> Questions:
> I am wondering if he is in Costa Rica and I get say Unlimitel.
> - How would I fugure latency before purchase, I want to make sure he
> is going to have low ping speeds to the unlimitel server (Do they have
> them spread all over the globe?)?
> Should I use a company in Costa Rica Instead of Unlimitel?
> - What should I be considering here how far to the Voip Provider
> server? How far is the call going on POST? What should be my deciding
> factors and parameters for choosing a provider?

I think Unlimitel probably has a server anywhere that it monetarily makes sense. I always pictured them with one main location, where their VoIP is, and small PRI-to-VoIP systems in places where it made more sense to co-lo that equipment than to backhaul a PRI. They give you an IP address to connect to and that's the one you use with your account.

That said I think your Costa Rica user will be connecting back to Canada. 

The factors in choosing an ITSP are many and you would be weighting them based on your own needs.

You want a certain number, ITSPs only carry limited phone number exchanges. You want Toronto or Cambridge. You can likely find hundreds of ITSPs that provide Toronto numbers, fewer that provide Cambridge.

Primarily you need a predictable connection. As long as the latency (ping time) is not crazily long you are okay. The key thing is that it be consistent. The higher the latency means a delay from when the other party talks and you hear and respond. A long delay sounds like a satellite connection with long delays between responses. If latency isn't consistent then delay between talk and echo changes and echo cancellers have to retrain. In short varying latency means more echo.

Throughput and packet loss are other metrics worth measuring if you're concerned. A safe value is that 64K is needed for a conversation. That's way high practically speaking but it won't be higher than that unless you're planning on doing video calls.

Then you need to consider the financial aspect. How much is the monthy, how much is LD, etc.

Then you need to consider the reliability of the ITSP. Are they down much, how is the quality, do they have redundancy features like forwarding if VoIP fails.

You could also obtain a Costa Rica ITSP so your employee, and your office can place local calls cheaply. Or pick up a PRI down there and start your own ITSP and sell Costa Rican LD.

John Van Ostrand 
CTO, co-CEO 
Net Direct Inc. 
564 Weber St. N. Unit 12, Waterloo, ON N2L 5C6 
Ph: 866-883-1172 x5102 
Fx: 519-883-8533 

Linux Solutions / IBM Hardware 

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