Does placing SIP calls over the Internet cause quality issues?

With SIP trunks, voice gets converted into IP packets. These IP packets then get sent to the SIP provider (and vice versa). Because voice is real-time sensitive, it requires that the voice packets arrive within a certain amount of time and in the right order (along with a number of other factors like jitter, packet loss, etc). If some of the voice packets get dropped or if they are sent too slow, audible quality issues can occur. So the quality of the connection between the customer’s phone system and the SIP provider directly affects the quality of the call. The connection between the customer’s phone system and the SIP provider varies. It can be a direct connection or over the Internet. The Internet is essentially a “network of networks” in which all types of data traffic (voice, video, email, web, etc) travel. Because the voice packets are “co-mingling” with other packets carrying various forms of information for different customers, it is considered a “best effort” form of delivery. This is why a dedicated connection between the customer’s network and the SIP provider is “technically” the best method for delivering SIP trunks. If that dedicated connection is also going to be used to send other types of data traffic (web surfing, email, etc), it needs to prioritize the voice packets over all other data packets (this is called Quality of Service). [ read more ]