A Voipswitch or softswitch is a very important device element of any
telecommunications network. It connects different IP networks in order to
deliver end-to-end communications
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.