Centralization of IT resources has been the path to lowest TCO, whether we are talking about application processing, or data storage. Centralization provides higher utilization of servers and reduces server costs, reduces operations costs including power, staffing and management and provides increased agility to accommodate network changes (e.g. new sites, unexpected growth, site decommissioning).
But obviously both centralized and distributed IP Telephony are viable options. So what are the key factors to consider.
In my mind there are five:
1. Remote Site Business Model: Are you employee or customer centric (remote offices or branches in my lingo), and/or are your sites run as under separate budgets or are they centrally budgeted?? This impacts service levels, as well as performance and feature needs.
2. Reliability, Business Continuity and Disaster Recovery: What is your business priority in terms of business continuity and disaster recovery? For example, you can have a call server a safe distance away, take over call processing when the primary server fails. For example, IP Telephony provides you new options to address business continuity shortcomings of traditional PBXs.
3. Scalability: Not a big deal for a medium enterprise, but if you are very large, centralization demands simplification, for example in number of servers required.
4. Reliability and Network Bandwidth: The key questions are how reliable is your IP network and at what cost can it be upgraded, and what is acceptable business impact in case of network failures.
5. Business Economics and Migration Risk: Balancing business needs with the network costs (which increase as reliability is enhanced) and IPT costs (which decrease as you centralize) is a critical factor in choosing between centralized and distributed solutions. Likewise investment protection can play a big role as well.
The two technology factors (#2 and #3) is why Nortel's CS 2100 solution is winning many very big deals: it delivers carrier-grade reliability with unmatched scalability to 200,000+ users on a single server and is well suited to data center deployments.
Whether you are a large multinational or a smaller regional enterprise, you should carefully assess your business needs and the degree of centralization and distribution that best meets these needs.