The TEIs for your telephone numbers are provided by your phone
company.
They are set on ControlCenter’s “ISDN Line” tab, just as your SPIDs
and telephone numbers were.
If you were not provided with specific TEIs, leave Automatic
Assignment set in the drop-down menus.
If you were provided with specific Terminal Endpoint Identifiers
for your telephone numbers, select Fixed Assignment from the
“TEI for Telephone Number 1 (DN1)” and “TEI for Telephone
Number 2 (DN2)” menus in the “Terminal Endpoint Identifier
(TEI)” section.
Then type the TEI for each telephone number in the text boxes
next to TEI drop-down menus.