New Flexible Code Restriction

NFCR controls the access of Toll Denied (TLD, CTD, CUN) stations and trunks to outgoing routes, based on the specific digit sequence dialed. This is useful for blocking certain digit strings (or area codes) when the route access code (ACOD) is used, assuming that TGAR has allowed access in the first place.

NFCR and Class of Service (CLS):

CTD, CUN	NFCR restrictions do not apply for BARS, NARS, CDP or ANI type calls. NFCR applies only on direct trunk access code (ACOD) type calls.
TLD	Users are always affected no matter how their call is dialed.

The FRL associated with the users NCOS is used to determine which codes are allowed or denied.
Stations are by default Conditionally Toll Denied (CTD). See also CLS Access Restrictions.

NFCR Implementation:

• A digit string list (CRNO) for each FRL level is set for a route in LD 16
• Initially, in each CRNO, all codes are either allowed or denied (INIT ALOW / DENY)
• Specific digit string exceptions (codes) are then allowed (or denied) as required in LD 49

LD 21, print FCR (FCR_DATA) to see is NCFR is enabled (default is disabled) - change FCR in LD 15.

REQ: prt
TYPE: fcr_data
CUST 0
 
TYPE FCR_DATA
CUST 00 
NFCR YES                      New Flexible Code Restriction is enabled!
  MAXT 100                    max. number of code restriction trees (LD 49: CRNO)
:

LD 87, NCOS - FRL map, often 1:1.
The FRL normally controls access to an RLI entry: FRL 0 is the most restrictive, 7 is the least restrictive and can access more entries. For a toll denied set dialing an ACOD, with NFCR YES, the FRL controls which code restriction tree is referenced for route access.

REQ  prt
CUST 0
FEAT nctl
NRNG 0 10                     enter a from-to NCOS range to print
 
SOHQ NO
SCBQ NO
 
NCOS 0                        NCOS value...
 
EQA  NO
FRL  0                        mapped to FRL value
:
  
NCOS 1                        NCOS value...
 
EQA  NO
FRL  1                        mapped to FRL value
:

LD 16, in the Route Data Block, an NFCR tree number (CRNO) is assigned to each Facility Restriction Level (FRL).
Scroll down to the FRL section, near the bottom of the RDB block to see the CRNO assignments. Default is 0:

:
FRL  0 0                      sets with FRL 0 will reference CRNO 0 
FRL  1 1                       "    "   FRL 1  "       "     CRNO 1
FRL  2 2                       "    "   FRL 2  "       "     CRNO 2
FRL  3 0                       ... etc
FRL  4 0 
FRL  5 0 
FRL  6 0 
FRL  7 0 
:

Use LD 49 to administer, and print, code restriction trees and digit string (NFCR) data.

Any digit sequences is initially (INIT) ALOWed or DENYed
Exceptions can be: DENY / ALOW / or BYPS (exceptions make the rule!)

• ALOW or DENY define a specific digit sequence to allow or block
• BYPS defines a digit sequence to bypass, though following digits may be blocked.

REQ  prt
TYPE fcr
CUST 0
CRNO 
 
CRNO  0                       code restriction tree number
INIT ALOW                     by default allow all codes
                              ← no exceptions
CRNO  1 
INIT DENY                     initially, deny all codes
ALOW 555                      ← exceptions, digit sequence to be allowed
     556
 
CRNO  2
INIT ALOW                     initially, allow all codes
DENY 1900                     ← exceptions, digit sequence to be denied
     
CRNO  3
:

LD 49 is also used for Incoming Digit Conversion.

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