What Is a Class of Service?
In IT, a class of service (CoS) is networking method of managing traffic by grouping various types of traffic by similarity and then prioritizing each type as a class with its own level of network service priority. In landline telephone systems, CoS defines permissions that an extension may have on a PBX so that companies can manage various options on groups of extensions.
Class of Service Examples for Telephone
Here are some examples of CoS in voice services:
Extending voicemail message retention to some users
Forwarding calls to cell phones
Limiting calls to within the office
Defining lines as inbound or outbound only
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