What is a T1 or E1? T1 and E1 refer to telephone trunks that
carry digitized voice in Time Domain Multiplexed (TDM) channels.
T1 based interfaces are pre-dominantly used in USA. Each T1 has
24 voice ports. E1 based interfaces are pre-dominantly used in
Europe, Asia and Latin America. Each E1 has 30 voice ports. One
voice port equates to one phone call. What is an ISDN PRI? T1
ISDN PRI refers to a T1 based trunk that uses 23 bearer time
slots and 1 signaling time slot. It is also popularly referred
to as 23B + D. E1 ISDN PRI refers to an E1 based trunk that uses
30 bearer time slots and 1 signaling time slot. It is also
popularly referred to as 30B + D. What is a VoIP/SIP trunk?
Voice over IP refers to carriage of voice calls over the
Internet. Session Initiation Protocol (SIP) is a signaling
protocol that is used for setting up VoIP connections. The
VoIP/SIP trunk operates over a standard Ethernet interface. What
interfaces does USN support? USN supports the following TDM
interfaces: - T1 ISDN PRI - T1 E&M Wi