Quite difficult to make a choice of many such things to each other. The more complex devices such as PBXs – to date market flooded nearly identical in its properties and functions of the device. So way is to rely primarily on what tasks you should perform the appropriate PBX. First, decide on a number of external lines will be connected to a PBX, as well as how many jobs will be equipped with telephones and fax machines. It is very important to represent and how to develop the telephone company's network in the future. It is necessary to choose a PBX that would "expand", but would not require replacement by a new model. For ATS is the definition of tasks to prepare in advance. At a minimum you need to know the number of jobs, the number of external lines and their type – analog, digital ISDN or E1-R2. For even more opinions, read materials from Howard Schultz.
Analog lines can be tone or pulse, and have action, that is to be equipped with the ARS – Automatic Route Selection. Also, the phone lines may be a different type of recruitment, different tariffs, and perhaps that day is better to use a single line, and in the evening – another. In this case, useful limited only to digital PBXs. Need to thoroughly determine all the parameters of a digital line, as not all digital PBX supports various types of alarm systems and interfaces. The next item – the definition of separate group of phones.
These include groups of consecutive poll, when the call comes first on one phone and if he is busy, goes to the other. Group general call, when they call all the phones. Groups automatic call distribution – in such a group calls are automatically distributed evenly among the operators. There are additional features of processing calls. Because direct access to the system allows to call a particular employee – the caller must dial tone after enter the extension number of the employee.