Packet switching is a method of sending information (data) over a network. Before being sent, the data is first divided into chunks (packets), which are sent individually across the network. When they reach the destination, they are reassembled back into the original block of information, and delivered to the user.
Here is an analogy to better understand: You have a large item to ship but only have small boxes. For each box, you add instructions (Box 1 of 6), the address and postage, and drop them all into a mailbox. Network packets are like the boxes except they contain data, sequence information, and a network (IP) address. Like packages in the mail, network packets may get separated in transit and arrive at different times. In a packet switched network, the recipient’s device waits for all the packets to arrive and reassembles them into the original information block before delivery to the user.
SIP (Session Initiation Protocol)
SIP is one of the VoIP protocols companies use. The role of SIP (in a VoIP call) is to establish a connection between the sender and receiver. This is a fixed route that simulates a circuit switched connection because it can only be used by the sender and receiver.
Once the SIP connection is in place, the other VoIP protocols will use it to send audio between both parties. When the call is over, SIP disconnects the session. A SIP connection may be referred to as a virtual path.
Analogy: Think of SIP as a highway road crew – they make sure the ramps are opened and the highway is in good repair, so vehicles can enter, drive, and exit. They are not concerned with the types of vehicles or their contents. Likewise, SIP creates a pathway (connection) for calls but does not interact with the contents (voice packets) of the call.
