Telecom questions

Here are some questions I want answers to:

1. How many phone lines are required per employee? One line per employee? One line for every five employees (this kind of thing obviously requires a PBX)?
2. Is it more cost effective to buy or lease a PBX? What about hosted PBX?
3. At what point is it more cost effective to use a PRI for voice instead of having analog lines? Or a T1 with half the channels for voice and half for data?
4. Can a very small organization with only one site save money with Internet telephony?
5. Can a small organization with multiple sites save money with Internet telephony?
6. When is frame relay a better choice for intersite data transport than a VPN over the public Internet?

Please comment if you have any answers for me. If I find my own answers I will add them here.

Comments

[Phil M]

1. The number of lines depends on the business type. Something like a call center will need a 1-1 ration of lines to employees. An IT consulting company can probably get away with 1-3 (especially if each has their own cellular phone), and someone who rarely makes or receives calls can probably get away with 1-6 or more. There's no hard and fast rule for this, of course.

2. I'm very interested in Asterisk, the open source PBX. If this is something that could be used by non-profits, then it would save them a lot of money if the phone systems were easy to maintain (web-based interface or somesuch). Otherwise, a low-end phone system with just handsets and voicemail for a couple hundred dollars per phone might be the best choice. Systems which offer Outlook integration and the like might offer nice features but will be an expensive administrative headache.

3. Phone companies will probably charge non-profits as a normal business, so even something like an analog phone line can be pretty pricey. A PRI line has 24 channels (lines), so that's overkill for most non-profits. A partial T1 which has four voice channels might be a good deal if the non-profit was planning on getting high-speed Internet connectivity.

4. I doubt it. Maybe with Asterisk in the future, but I don't think that it's here today. The human-telephone interface is far easier to learn than the human-computer-telephone one.

5. Like the question above, I don't think Internet telephony is really ready for use in an office. Maybe for one person working at home, but not for multiple people. The bandwidth and administration requirements are going to be prohibitive. Not to mention that if you don't think the non-profits computers are reliable, why add a phone system on top of them? Additionally, calls to a remote site could pass through multiple points of failures (ISPs), where a regular land-line call will only go through maybe one or two. Frankly, I have seen Internet connectivity on T1s go down far more often than the voice connectivity (even on PRI lines).

6. Dunno about this one, although if I did have to setup VPN, I'd rather it be dealt with by the routers rather than by the clients/serveres.