This time we will analyze what are the main characteristics to take into consideration when choosing codecs for communication systems.
Codec stands for coder-decoder. A codec codes a signal into a digital data stream and decodes a digital stream into a signal.
In the case of VoIP, when choosing a codec, we are mainly interested in two characteristics:
- Amount of bandwidth used
- Quality
Adequate bandwidth is necessary for a high-quality conversation. Even when implementing jitter buffers and packet loss concealment in the endpoint, if the current connectivity cannot withstand the traffic transmitted over it, there is going to be huge packet loss, making it impossible for users to have a conversation.
The SIP specification has been extended over time to support a general mechanism allowing for subscription to asynchronous events. Such events can include SIP proxy statistics changes, presence information, session changes and so on.
ACK method confirms that an entity has received a final response to an INVITE request. In its turn, BYE method signals termination of a dialog and ends a call.
Calls are started by means of the methods INVITE
SIP is a peer-to-peer protocol