Line short codes are used if Small Community Networking (SCN) is not being used or no SCN user extension match occurs on the digits received. If no line short code match occurs then normal incoming call routing is applied.
E1 and BRI ETSI Trunks
These types of trunks use line short codes immediately. If no short code match occurs then normal incoming call routing is applied.
QSIG and SO Trunks
S0 trunks, and E1 and T1 trunks set to QSIG mode, use line short code if the digits received do not match an internal extension number. These types of trunk do not use incoming call routing.