a

accounting codes

anonymous call rejection

attendant consoles

automated attendant

automated call distribution

c

caller ID

call barring

call blocking, selective

call center functionality

call logs (missed, dialed, received)

call pickup groups

call waiting

conference calling, 3-way

CRM integration

d

direct inward dialing

distinctive ringing

do not disturb

directed call pickup

dynamic bandwidth allocation

e

ethernet switch, commercial grade

extension dialing

f

find-me, follow-me

firewall, managed

Forwarding (immediate, delayed, busy, selective)

h

hold

hunt groups

i

intercom

internet access, high speed

l

line and extension monitoring

long distance bundles

m

multi-line hunt groups

multiple appearance directory numbers

music on hold

mute

automated call distribution

p

park orbits

priority line

q

quality of service prioritization

r

redial

s

shared line appearance

sim-ring

softphone client

speed dial

speakerphone, duplex

t

T1 connection

transfer

u, v, w, x, y, z

unified messaging

voicemail