Interconnection of PBX

The extension and interconnection of PBX, with networking services, could be done by several solutions using the following interfaces

• E&M per analog interconnection with one communication
  
• E1 CAS to E1 CAS to 30 communications simultaneously
  
• ISDN PRI up to 30 communications simultaneously
  
• ISDN BRI up to 2 communications simultaneously

This line extension could be realize with coppers wire, fiber optic, PDH, SDH networks, IP, or over leased line and Frame Relay networks.

• Analog links with E&M, or of E1 CAS described in "Analog voice extension"
  
• ISDN BRI (S0/T0) to BRI described in "Extention of digital voice over ISDN"
  
• ISDN PRI to BRI (S0/T0) described in "ISDN distribution"