AT&T 993 2-Line - Manual (Page 13)

0
Getting started
Connect the telephone line cord(s) to the telephone and the modular
wall jack(s).
If there is a single two-line modular wall jack, use only the black
telephone line cord (4-conductor). Plug one end into the jack labeled
L1 or L1/L2 on the back of the telephone. Plug the other end into the
wall jack. Make sure the telephone line cord snaps firmly into place at both
ends.
1.
Telephone installation
Two-line modular
wall jack
Black telephone line
cord (4-conductor)
If there are two one-line wall jacks, use both telephone line cords. Insert
one end of the clear telephone line cord into the jack labeled
L1 or L1/L2
on the back of the telephone. Plug the other end into the modular wall
jack for Line . Insert one end of the black telephone line cord into the
jack on the back of the telephone labeled
L2. Then, plug the other end into
the modular wall jack for Line 2. Make sure the telephone line cords snap
firmly into place at both ends.
Modular
wall jack for
Line 
Modular wall
jack for Line 2
Clear telephone
line cord
Black telephone line
cord (4-conductor)