* concurrent calls
This is the number of calls you would like to be able to handle at the same time. Additional callers would hear the engaged tone.

Often, one two or three concurrent calls will be sufficient unless you expect many simultaneous calls at peak times. The Erlang model allows you to calculate more accurately your requirement, but a general guide is to set it to the number of operators you would hire to operate the lines.

† application complexity
This is an estimate where you think your application fits in terms of its complexity. To allow you to make an initial judgement, we've shown the applications from the try it page in the list. In general, it is dependent on:

• The complexity of the dialogue - how many different questions are asked?
• The complexity of the grammars (more) - are they standard or mostly bespoke?
• The number of times we need to interface with your and other systems to retrieve or to store data.

If you're not sure, please contact us with a description of your application and we'll be happy to help.