Delivering Call Quality with VoIP
From: The VoIP Essentials Series
By: Ken Camp
Over the past hundred years, the public switched telephone network (PSTN) has evolved into a finely tuned mechanism for delivering voice traffic. In business, for years the phrase “toll quality voice” has been used to describe a service level suitable for business—good enough to hear a pin drop. This network has been built and conditioned to do one thing really well—deliver voice conversations.
Data networks use Internet Protocol (IP) for delivery. IP is described as being unreliable and having no guarantees. It is a “best efforts” protocol. It was designed to carry sporadic, unpredictable traffic loads that burst to peak volumes at times. At that transport layer, above IP, there is also Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). TCP offers the ability to guarantee delivery through a process of synchronization and acknowledgement messages, but this delivery guarantee also adds overhead to the data flow. Table 1 provides a comparison of voice and IP traffic.
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