Sizing & Licensing

The licensing model is per server port, regardless of the number of users.

Licenses are attached to the machine running the Dial On Phone server.

A Twin license is for a single active Dial On Phone server and its hot stand-by peer.

A Cluster license is for several active Dial On Phone servers.

Contact me for conditions.

A single port can carry several simultaneous click-to-dial requests and the required number of ports can be computed with a classic Erlang B calculator or an extended Erlang B calculator.

In transfer mode (the Dial On Phone solution does not bridge calls), the Busy Hour Trafic (BHT) can be assesed like this :

BHT = (1 / Monitoring period in seconds) * (Number of click-to-call attempts per user during the monitoring period * Average call setup time in seconds * Number of users) in Erlangs

For instance :

Monitoring period = 60 min

Number of click-to-call attempts per user during the monitoring period = 4

Average call setup time in seconds = 20s

Number of users = 200

BHT = (1/3600) * 4 * 20 * 200 = 4.45 Erlangs

With a call blocking rate of 1%, the Erlang B formula computes the minimum required number of ports to 10.

In bridge mode, the port is used during the whole duration of the call (not only during the call setup phase), as a consequence more ports are required. This mode is also much more process intensive than the transfer mode, but the load can be balanced across several servers.

It is also very much possible to mix transfer and bridge mode -typically transfer mode for the tel protocol (PSTN numbers) and bridge mode for internet voip protocols.