point-to-point dedicated digital circuit provided by the telephone companies consisting of 24 channels. E1 The European counterpart to T1 which transmits at 2.048 Mbps TAPI Telephony API A programming interface that allows Windows client applications to access voice services on a server. 802.1p An IEEE standard for providing QoS using three bits (defined in 802.1q) to allow switches to reorder packets based on priority level. TOS Type of Service A method