Is there an accepted Grade of Service standard for Call Centers? If so, where is it in print?
My informal understanding is that Telecom trunking and PBX design standards for Call Centers is .01. I have found no information in print to support this as a verifiable and concrete standard rather than an accepted practice.
As Erlang C is generally the accepted model for traffic analysis on a call center. Since the blocked call disposition is delayed and not held or cleared, blocking is not a factor.
service time or delay would depend on your business model…30seconds to 90 seconds Avg. Speed to Answer (ASA) is what I have used in the past but then again I have had call centers that strive for 7-10 second ASAs.