210 Creating numbering plansN0008589 3.3Incoming callsIncoming call handling also depends on the call type. The system also uses the Public and PrivateDN # length settings to determine call handling. Refer also to “Defining DN length” on page 294.The system processes a call in the following way:1 The system receives a call from the public or private network.2 The system identifies the call type:Public calls:• If the call is from the MCDN network and is a local, national, or special call type, thesystem prepends the appropriate access code.• If the call is from ETSI-QSIG, MCDN, NI-2, DMS100, DMS250) and tagged asPrivate/Subscriber, the system prepends the Private access code, if the dialing plan is UDP.• If the call is tagged as Unknown/Unknown or Private/Unknown (ETSI-QSIG, MCDN, N1,DMS100, DMS250 trunks), no access code is added.• For all other call types, the system truncates the trailing digits to the Public Received #Length. (Go to step 5)Private calls:• If the call is tagged as Private/Subscriber or Private/UDP, the system prepends the Privateaccess code.• If the call is tagged as Private/CDP, no access code is added.3 The system tries to match the first digit(s) of the dial string to a destination code. If the digit(s)matches, the dial string is routed out of the system.4 If the system cannot match the first digit(s) to a destination code, it truncates the trailing digitsto the Public Received # length or Private Received # length, as appropriate to the call type.5 The system again tries to match the leading digit(s) to a destination code. If the digit(s) match,the dial string is routed out of the system.6 If the system cannot match the first digit(s) to a destination code, the system tries to match thedial string to a target line (Public or Private Received Number). If the dial string does notmatch any target lines, the call is routed to the prime line.Refer to the figure below for a graphic illustration of incoming call processing.
