Specifications

Typical Configurations
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• Call volume is typically split in thirds, with 33% incoming from trunks, 33% outgoing to
trunks, and 33% handling internal calls (50% is making calls and 50% receiving calls).
• For normal users, typically one voice mail session is needed for 20 users. Modify this number
accordingly if you expect heavier or lighter voice mail traffic per user.
• Typically, ACD workers are busy 75% to 100% of the time. One ACD agent normally requires
one resource, such as one 1 E2T channel, one echo channel, one DSP channel (compres-
sion), and one trunk. ACD traffic ranges from 27 to 36 CCS (27 to 36 calls per hour).
• Typically, in a given ACD group, all calls are either incoming or outgoing trunks, rarely mixed.
• Traffic blocking is calculated using the ErlangB formula. Erlang adds a statistical blocking
factor and is always higher than the straight calculation. Add a further 10% to 20% to PI
estimates as a rough estimate, and round up.
• Operators or attendants can typically handle up to 100 calls per hour (as long as transfer
is handled quickly and number lookup is sufficiently quick). Most incoming trunk calls arrive
at the operator station.
• Traffic blocking probability for internal/intercom traffic is P.001 (1 in 1000 calls blocked).
• Traffic blocking probability for trunk traffic is P.01 (1 in 100 calls blocked).