Early in their development, LAN-based PBXs had a couple of key limitations, such as the number of users the combined network could support. But today's PBX products can support thousands of users, with the promise of nearly unlimited numbers of users in the next generations of products. For example, Sphere Communications' Sphericall, a product announced this past February, supports up to 15,000 telephone users.
Corporate users also had concerns about quality of service (QOS) and reliability issues related to network PBXs. System vendors and users report, however, that the reliability of newer systems is excellent, often reaching the "five nines" level of 99.999 percent uptime. Many vendors recommend running their PBX systems on separate servers, rather than sharing a server with other networked applications. This practice dramatically decreases the potential clash of data and communication systems. Vendors also often provide recommendations for hardware based on their compatibility and reliability testing.
In addition, network PBXs now generally support standard analog telephones, rather than requiring specialized digital units. This can represent a significant cost savings, as digital handsets can run hundreds of dollars, compared to $20 for a standard analog handset and up to about $100 for a full-featured, dual-line model.
