Is a telephony service allowing the distribution of telephone calls from one telephone number in the group consisting from several telephone lines, using the special algorithm, which determines the line receiving a call.
SIP-addressing is logical, of the same type as URL in HTTP. And the most natural – to use the electronic mail as the SIP address. There are permissible varied parameters by the address: for example, it is possible to indicate the regular city telephone number, additional telephone, and the parameters of modem connection etc.