In this section you learned:

• ISDN devices need to have unique addresses
• These addresses are known as TEIs
• An address is nothing to do with the telephone number
• PRI lines permit only a single device at address TEI 0
• BRI lines can have either fixed or dynamic address assignment
• Fixed address lines permit only one device
• Dynamically assigned lines can have up to eight TEIs
• Mixing TEI assignment types can result in communication failures