- You are not running CAS (Layer 2 statistics for CAS indicate whether a line is blocked, back busied, or not).
- You are not connecting a user side port to another user side port (or alternatively, a network side port to a network side port).
- Occasionally, on certain protocols, the Layer 2 can take up to a minute before it becomes active. If you have been waiting for this time and are certain everything is configured correctly, it maybe worthwhile attempting to make a call. This can sometimes force Layer 2 to be activated. If running SS7, check that the point codes have been configured correctly and have been applied (when downloading firmware) in the decimal form.
- When using ETS300, one can request that the ETS300 firmware attempt to force Layer 2 up by adding the firmware switch '-s60,1'