1) Relocating to a new office
If you don't have any pre-existing infrastructure to worry about, fitting up a new office is the perfect opportunity to implement VoIP, regardless of your voice requirements because you have to fit out a network infrastructure anyway, no matter how basic. If you followed the traditional model of voice/network infrastructure, you'd have to cable everything up for network communications and lay a separate run of cabling for voice communications. Not to mention the cost of either a dedicated line to the exchange, or a trunk line and local PBX.

2) Existing single office with no PBX
This scenario fits the description of only the smallest of offices with perhaps only one incoming line, much like a residential connection. The benefits of VoIP here are not clear-cut. If you have an Internet connection, it would certainly be worth considering approaching the ISP to see what broadband VoIP deals they can offer. This would give you the flexibility to have multiple handsets on the one line or even a VoIP-capable mobile running off a wireless network. However the decision is more likely to be made on the grounds of functionality and consolidation rather than cost. The cost differential between traditional voice and VoIP is likely to be negligible.

3) Existing single office with a local PBX with single trunks
If this is the case then stick with what you have for the time being until it's time to upgrade, and then future-proof your requirements by spending the money on VoIP. Until that time it's unlikely to be worth the cost. If you're not satisfied with the current system and were looking at upgrading anyway, VoIP is definitely a good move. You'll still need the trunk to the exchange for PSTN connection, but you'll get the internal benefits of running VoIP.

4) More than one office with local PBX at each and multiple trunks
This is a scenario where VoIP truly shines. Each office has a requirement for a local PBX to minimize costs and meet internal voice requirements and as already mentioned, even a VoIP-enabled system eventually requires access to the PSTN. But what you can do is leverage off each office's Internet connection to set up VPN's across the WAN links between each office, effectively making them part of the same network. Upgrade each office to VoIP, have one office hosting the trunk to the PSTN, and route all external calls through this one connection. Slash costs and make every employee's extension effectively internal.

The wonderful advantage of voip is that if a device fails, it's relatively easy to bypass it just by pointing the servers to another gateway and have them disseminate the information to the client machines, plug cables into another switch, rig up a temporary wireless connection, hang a cable from the ceiling anything works. Upgrades are easy and are often done entirely in software so no new hardware required, and telephony capabilities are much more dependent on the individual handsets. By comparison a telephone network is static, inflexible and relies almost totally on the switching hardware for capability and capacity.

However, careful calculation is crucial before an organization decides to switch to VoIP telephony system.

1)when should a business switch to VoIP telephony system?

2)when a business involves significant call charges

3)when a business needs to make significant overseas calls

You can avail the benefits of the VoIP technology even with the conventional fully featured telephone system currently present in your set up. You need to use routers to achieve seamless VoIP integration into your business. It needs to be noted that VoIP routers are suitable for small enterprises that require a simple entry level VoIP solution. Routers will not turn out to be an effective solution where the organization involved is exceptionally large and operates a very complex telephone system.

VoIP for businesses (commercial VoIP) should be selected with utmost care. Selection of a right VoIP service provider is crucial as the success of the commercial VoIP will depend significantly upon the service provider you choose. VoIP solutions come in many shades and flavors. There are fully hosted solutions, partially hosted solutions, locally hosted solutions, true VoIP, partial VoIP, IP-capable PBX units, softPBX devices, VoIP servers, messaging gateways and the list just goes on and on. The best solution for one business is unlikely to suit the business next door. So, the best first step is to seek advice from industry experts or VoIP solution providers and system integrators.

If you have a small business and your voice requirements are minimal, investigate what your ISP has to offer. Many ISPs are offering broadband based VoIP solutions, and they're generally pretty good. See what features you'll receive, how the call costs compare to your current plan and whether you'd make savings over time. This way, you don't have to worry about implementing a local solution when someone else takes care of everything. For medium businesses and larger, the options are simply too varied to list comprehensively in one spot. Each vendor will offer you a different package, different solutions, different hardware, different software products, different features, hosting options and support agreements.

The best course of action is to approach a small number of VoIP integrators to get an overview from each one as to what is likely to be suitable for your business, and compare them. If they're any good, the proposals should be fairly close to each other, which makes it easy to discard any obviously inflated quotes. Start with your current voice carrier as all major telephone companies now offer VoIP solutions for business.

However, you can start getting to grips with VoIP in the office by setting up a test environment and involving a few key users to test messaging functionality, service integration and hardware. You can easily set up a software-based PBX server for free, get hold of some handsets and softphone applications and start assessing their value.