This voice technology typically uses standard codecs like G.711, which is the standard when transmitting uncompressed packets. The G.729 codec is commonly used when transmitting compressed packets. There are also many proprietary codecs used by equipment vendors and although voice quality may sometimes suffer when compression is used, it significantly reduces bandwidth usage.
Once the data is transmitted via IP, Real-Time Transport Protocol (RTP) is typically used. Session Initiation Protocol, or SIP, is often used when it’s necessary to start or end a call.
There are other typical components necessary to use VoIP services, such as an IP PBX to manage telephone numbers, gateways to connect networks, and session border controllers that provide network connections and security. A VoIP system can also make use of location-tracking, such as E911 (enhanced 911), to collect call statistics for proactive and reactive management.