IP-based System vs Traditional PBX

Total cost of Ownership

This depends much on the size of the organization. In small offices most VoIP

systems are little more expensive than a small PBX of key telephone systems (KTS).

In large offices it would be about the same. But adding redundancy in a VoIP

system means addition of surveys and this can make the system much expensive

them a large PBX. However, if one factors in all the additional usable features,

invariably an IP-PBX system comes out more cost effective. Additionally as the

number of users per location increases, the cost advantage dramatically tilts in

favor off IP-PBX as the incremental investments in an IP based infrastructure

are absolutely linear, as opposed to traditional PBX’s where increments are in

exponential steps. Another advantage in favor of IP-PBX, is that it is

completely standards based, and all the various components inter-operate in a

vendor independent manner. Thus not locking the user into any one vendor.

Quality of service

This depends much on the data network. The quality of VoIP voice is as good

if not better than PBX systems if the data network is well designed and not

heavily loaded. Once VoIP or IP telephony solution is installed and optimized,

end users are usually oblivious to whether or not the call is over an IP

infrastructure or over a circuit switched network. In fact, QoS is a concern on

shared networks and not in the case of managed IP networks.

Operational cost

This is where VoIP shines the most. These systems make moves, adds and

changes very simple. You can just pick up a phone and plug in anywhere on the

LAN and it automatically registers with the call servers. The server then sends

all your calls to that phone. In some systems it is possible to log on to the

network from any phone. Moves, adds and changes are one of the largest

operational expenses in a telephone network and VOIP can almost eliminate it.

Also, a converged solution means lower cost as compared to operating two

separate infrastructures.

Efficiency

If addressed from a perspective of increasing user productivity, the IP

approach is definitely more efficient as it enables new generation services like

collaboration, unified messaging, follow me anywhere, et all.

In terms of bandwidth efficiency, in case the voice on the network is

compressed, VOIP can meet, or even beat traditional systems. However, if you do

not compress it, VoIP would use 25-30% more bandwidth due to packed and

signaling overheads.

Ease of administration and manageability

Extremely user friendly and can be handled by any body due to the

availability of GUI-based interfaces for administration and management of a

standard PC platform.