| CAA | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CAB | Anthem BCBS of Wisconsin (WI) |
| CAC | Anthem BCBS of Missouri (MO) |
| CAD | BCBS of Massachusetts (MA) |
| CAE | Empire BCBS of New York (NY) |
| CAF | BCBS of Mississippi (MS) |
| CAG | Blue Shield (BS) of California |
| CAH | Anthem BCBS of Georgia (GA) |
| CAI | Anthem Blue Cross(BC) of California (CA) |
| CAJ | Wellmark |
| CAK | Blue Shield (BS) of California |
| CAL | BCBS of Minnesota (MN) |
| CAM | Highmark BCBS of West Virginia (WV) |
| CAN | BCBS of Illinois (IL) |
| CAO | Unassigned Prefix |
| CAP | BCBS of Texas (TX) |
| CAQ | Premera BCBS of Alaska (AK) |
| CAR | Anthem BCBS of Wisconsin (WI) |
| CAS | BCBS of Texas (TX) |
| CAT | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CAU | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CAV | Premera BCBS of Alaska (AK) |
| CAW | Blue Shield (BS) of California |
| CAX | Anthem Blue Cross(BC) of California (CA) |
| CAY | BCBS of Massachusetts (MA) |
| CAZ | BCBS of Minnesota (MN) |
| CBA | Anthem Blue Cross(BC) of California (CA) |
| CBB | BCBS of Texas (TX) |
| CBC | Unassigned Prefix |
| CBD | Highmark BCBS of Pennsylvania (PA) |
| CBE | Unassigned Prefix |
| CBF | Anthem BCBS of Ohio (OH) |
| CBG | BCBS of Alabama (AL) |
| CBH | Anthem BCBS of Colorado (CO) |
| CBI | Anthem BCBS of Ohio (OH) |
| CBJ | BCBS of South Carolina (SC) / Southcarolinablues |
| CBK | Anthem BCBS of Ohio (OH) |
| CBL | Unassigned Prefix |
| CBM | Anthem Blue Cross(BC) of California (CA) |
| CBN | Unassigned Prefix |
| CBO | BCBS of Louisiana(LA) |
| CBP | Anthem BCBS of Ohio (OH) |
| CBQ | Anthem Blue Cross(BC) of California (CA) |
| CBR | Anthem BCBS of Wisconsin (WI) |
| CBS | Anthem BCBS of New Hampshire (NH) |
| CBT | Anthem BCBS of Ohio (OH) |
| CBU | Horizon BCBS of New Jersey (NJ) |
| CBV | BCBS of Louisiana(LA) |
| CBW | Anthem BCBS of Colorado (CO) |
| CBX | Unassigned Prefix |
| CBY | BCBS of Illinois (IL) |
| CBZ | Horizon BCBS of New Jersey (NJ) |
| CCA | Empire BCBS of New York (NY) |
| CCB | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CCC | Blue Cross (BC) of Idaho (ID) |
| CCD | BCBS of South Carolina (SC) / Southcarolinablues |
| CCE | Unassigned Prefix |
| CCF | BCBS of Illinois (IL) |
| CCG | Unassigned Prefix |
| CCH | Wellmark |
| CCI | BCBS Blue Care Network Michigan (MI) |
| CCJ | BCBS Blue Care Network Michigan (MI) |
| CCK | BCBS of Minnesota (MN) |
| CCL | BCBS of Illinois (IL) |
| CCM | BCBS of Texas (TX) |
| CCN | Unassigned Prefix |
| CCO | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CCP | Unassigned Prefix |
| CCQ | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CCR | Wellmark |
| CCS | Unassigned Prefix |
| CCT | Unassigned Prefix |
| CCU | Unassigned Prefix |
| CCV BCBS Prefix | Anthem Blue Cross(BC) of California (CA) |
| CCW | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CCX | BCBS of Minnesota (MN) |
| CCY | Wellmark |
| CCZ | Blue Shield (BS) of California |
| CDA | BCBS of Illinois (IL) |
| CDB | Unassigned Prefix |
| CDC | BCBS of Arizona (AZ) |
| CDD | Unassigned Prefix |
| CDE | Unassigned Prefix |
| CDF | Anthem BCBS of Kentucky (KY) |
| CDG | Wellmark |
| CDH | Unassigned Prefix |
| CDI | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CDJ | Anthem BCBS of Indiana (IN) |
| CDK | Empire BCBS of New York (NY) |
| CDL | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CDM | Highmark BCBS of Pennsylvania (PA) |
| CDN | Arkansas (AR) Blue Cross |
| CDO | Wellmark |
| CDP | Wellmark |
| CDQ BCBS Prefix | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CDR | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CDS | Blue shield(BS) of Northeastern New York (NeNY) |
| CDT | Anthem BCBS of Connecticut (CT) |
| CDU | BCBS of Illinois (IL) |
| CDV | BCBS of South Carolina (SC) / Southcarolinablues |
| CDW | BCBS of Massachusetts (MA) |
| CDX | BCBS of Illinois (IL) |
| CDY | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CDZ | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CEA | Anthem BCBS of Virginia (VA) |
| CEB | Wellmark |
| CEC | BCBS of Illinois (IL) |
| CED | BCBS of Illinois (IL) |
| CEE | BCBS of Texas (TX) |
| CEF | Anthem BCBS of Ohio (OH) |
| CEG | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CEH | BCBS of Massachusetts (MA) |
| CEI | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CEJ | BCBS of Illinois (IL) |
| CEK | Unassigned Prefix |
| CEL | BCBS of Massachusetts (MA) |
| CEM | Anthem Blue Cross(BC) of California (CA) |
| CEN | Unassigned Prefix |
| CEO | BCBS of Nebraska (NE) |
| CEP | BCBS Prefix/ BCBS of Illinois (IL) |
| CEQ | Wellmark |
| CER | Unassigned Prefix |
| CES | BCBS of Louisiana(LA) |
| CET | Blue Shield (BS) of California |
| CEU | Unassigned Prefix |
| CEV | BCBS of Illinois (IL) |
| CEW | Wellmark |
| CEX | BCBS of Illinois (IL) |
| CEY | BCBS of Illinois (IL) |
| CEZ | BCBS of Illinois (IL) |
| CFA | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CFB | Wellmark |
| CFC | Anthem BCBS of Georgia (GA) |
| CFD | Anthem BCBS of Indiana (IN) |
| CFE | BCBS of South Carolina (SC) / Southcarolinablues |
| CFF | Highmark BCBS of Pennsylvania (PA) |
| CFG | BCBS of North Carolina (NC) |
| CFH | Anthem Blue Cross(BC) of California (CA) |
| CFI | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CFJ | Wellmark |
| CFK | Wellmark |
| CFL | BCBS of South Carolina (SC) / Southcarolinablues |
| CFM | BCBS of Massachusetts (MA) |
| CFN | BCBS of Massachusetts (MA) |
| CFO | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CFP | Unassigned Prefix |
| CFQ | Unassigned Prefix |
| CFR | BCBS of Illinois (IL) |
| CFS | Horizon BCBS of New Jersey (NJ) |
| CFT | Empire BCBS of New York (NY) |
| CFU | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CFV | Wellmark |
| CFW | Unassigned Prefix |
| CFX | Premera BCBS of Alaska (AK) |
| CFY | Anthem BCBS of Ohio (OH) |
| CFZ | Anthem BCBS of Ohio (OH) |
| CGA | Anthem Blue Cross(BC) of California (CA) |
| CGB | Blue Shield (BS) of California |
| CGC | BCBS of South Carolina (SC) / Southcarolinablues |
| CGD | Blue Shield (BS) of California |
| CGE | BCBS of Texas (TX) |
| CGF | BCBS of Arizona (AZ) |
| CGG | Anthem BCBS of Kentucky (KY) |
| CGH | Anthem BCBS of Missouri (MO) |
| CGI | Wellmark |
| CGJ | BCBS of Massachusetts (MA) |
| CGK | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CGL | BCBS of Minnesota (MN) |
| CGM | Unassigned Prefix |
| CGN | BCBS of Nebraska (NE) |
| CGO | BCBS of Illinois (IL) |
| CGP | Excellus BCBS of New York (NY) |
| CGQ | BCBS of North Carolina (NC) |
| CGR | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CGS | Anthem BCBS of Missouri (MO) |
| CGT | Anthem BCBS of Connecticut (CT) |
| CGU | Unassigned Prefix |
| CGV | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CGW | BCBS of Minnesota (MN) |
| CGX | Anthem BCBS of Missouri (MO) |
| CGY | Florida (FL) Blue |
| CGZ | Anthem BCBS of Ohio (OH) |
| CHA | BCBS of Alabama (AL) |
| CHB | BCBS of Massachusetts (MA) |
| CHC | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CHD | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CHE | Unassigned Prefix |
| CHF | BCBS of Texas (TX) |
| CHG | BCBS of Illinois (IL) |
| CHH BCBS Prefix | BCBS of Tennessee (TN) |
| CHI | Unassigned Prefix |
| CHJ | Unassigned Prefix |
| CHK | Wellmark |
| CHL | Anthem BCBS of Ohio (OH) |
| CHM | BCBS of Nebraska (NE) |
| CHN | Unassigned Prefix |
| CHO | BCBS of Louisiana(LA) |
| CHP | Capital Blue Cross of Pennsylvania (PA) |
| CHQ | Anthem BCBS of Kentucky (KY) |
| CHR | BCBS of Illinois (IL) |
| CHS | BCBS of North Carolina (NC) |
| CHT | BCBS of Tennessee (TN) |
| CHU | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CHV | BCBS of Illinois (IL) |
| CHW | Unassigned Prefix |
| CHX | BCBS of North Carolina (NC) |
| CHY | BCBS of South Carolina (SC) / Southcarolinablues |
| CHZ | Unassigned Prefix |
| CIA | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CIB | BCBS of Illinois (IL) |
| CIC | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CID | BCBS of North Carolina (NC) |
| CIE | Wellmark |
| CIF | BCBS of Illinois (IL) |
| CIG | Unassigned Prefix |
| CIH | Carefirst BCBS of Maryland (MD)/District of Columbia (DC) and Northern Virginia (VA) |
| CII | Anthem BCBS of Georgia (GA) |
| CIJ | Blue Cross (BC) of Idaho (ID) |
| CIK | Capital Blue Cross of Pennsylvania (PA) |
| CIL | Unassigned Prefix |
| CIM | Unassigned Prefix |
| CIN | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CIO | Capital Blue Cross of Pennsylvania (PA) |
| CIP | BCBS of Alabama (AL) |
| CIQ | BCBS of Tennessee (TN) |
| CIR | Premera BCBS of Alaska (AK) |
| CIS | Regence BCBS |
| CIT | Florida (FL) Blue |
| CIU | Anthem BCBS of Virginia (VA) |
| CIV | Capital Blue Cross of Pennsylvania (PA) |
| CIW | Anthem BCBS of Indiana (IN) |
| CIX | Anthem BCBS of Missouri (MO) |
| CIY | Florida (FL) Blue |
| CIZ | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CJA | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CJB | BCBS of Illinois (IL) |
| CJC | Anthem BCBS of Ohio (OH) |
| CJD | Unassigned Prefix |
| CJE | Empire BCBS of New York (NY) |
| CJF | BCBS of Nebraska (NE) |
| CJG | BCBS of Kansas City |
| CJH | BCBS of North Carolina (NC) |
| CJI | Highmark BCBS of West Virginia (WV) |
| CJJ | Premera BCBS of Alaska (AK) |
| CJK | BCBS of Massachusetts (MA) |
| CJL | Empire BCBS of New York (NY) |
| CJM | Florida (FL) Blue |
| CJN | Florida (FL) Blue |
| CJO | Anthem BCBS of Ohio (OH) |
| CJP | Unassigned Prefix |
| CJQ | Blue Cross (BC) of Idaho (ID) |
| CJR | Anthem BCBS of Wisconsin (WI) |
| CJS | BCBS of Illinois (IL) |
| CJT | BCBS of Texas (TX) |
| CJU | BCBS of Illinois (IL) |
| CJV | Empire BCBS of New York (NY) |
| CJW | Unassigned Prefix |
| CJX | Anthem BCBS of Ohio (OH) |
| CJY | Anthem BCBS of Ohio (OH) |
| CJZ | Wellmark |
| CKA | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CKB | Anthem BCBS of Ohio (OH) |
| CKC | Unassigned Prefix |
| CKD | Unassigned Prefix |
| CKE | Blue Shield (BS) of California |
| CKF | Unassigned Prefix |
| CKG | BCBS of Tennessee (TN) |
| CKH | Anthem BCBS of Indiana (IN) |
| CKI | Anthem BCBS of Georgia (GA) |
| CKJ | Anthem BCBS of Indiana (IN) |
| CKK | Unassigned Prefix |
| CKL | Carefirst BCBS of Maryland (MD)/District of Columbia (DC) and Northern Virginia (VA) |
| CKM | Highmark BCBS of Pennsylvania (PA) |
| CKN | Regence BCBS |
| CKO | BCBS of Massachusetts (MA) |
| CKP | BCBS of Texas (TX) |
| CKQ | Anthem BCBS of Ohio (OH) |
| CKR | BCBS of Tennessee (TN) |
| CKS | Anthem BCBS of Missouri (MO) |
| CKT | Unassigned Prefix |
| CKU | Anthem BCBS of Ohio (OH) |
| CKV | Anthem BCBS of Ohio (OH) |
| CKW | Anthem BCBS of Indiana (IN) |
| CKX | Blue Shield (BS) of California |
| CKY | Blue Shield (BS) of California |
| CKZ | Unassigned Prefix |
| CLA | Unassigned Prefix |
| CLB | BCBS of Illinois (IL) |
| CLC | BCBS of South Carolina (SC) / Southcarolinablues |
| CLD | Anthem BCBS of Georgia (GA) |
| CLE | BCBS of Texas (TX) |
| CLF | Anthem BCBS of Georgia (GA) |
| CLG | Unassigned Prefix |
| CLH | Excellus BCBS of New York (NY) |
| CLI | Wellmark |
| CLJ | Anthem BCBS of Ohio (OH) |
| CLK | Unassigned Prefix |
| CLL | Anthem Blue Cross(BC) of California (CA) |
| CLM | Wellmark |
| CLN | BCBS of North Carolina (NC) |
| CLO | BCBS of Mississippi (MS) |
| CLP | Unassigned Prefix |
| CLQ | Unassigned Prefix |
| CLR | Premera BCBS of Alaska (AK) |
| CLS | BCBS of Massachusetts (MA) |
| CLT | Wellmark |
| CLU | Anthem BCBS of Virginia (VA) |
| CLV | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CLW | Anthem BCBS of Georgia (GA) |
| CLX | Unassigned Prefix |
| CLY | Wellmark |
| CLZ | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CMA | BCBS Blue Care Network Michigan (MI) |
| CMB | Anthem BCBS of Virginia (VA) |
| CMC | Wellmark |
| CMD | Anthem BCBS of Missouri (MO) |
| CME | BCBS of Illinois (IL) |
| CMF | Wellmark |
| CMG | Wellmark |
| CMH | BCBS of Tennessee (TN) |
| CMI | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CMJ | Anthem BCBS of Indiana (IN) |
| CMK | Anthem BCBS of Ohio (OH) |
| CML | Unassigned Prefix |
| CMM | BCBS of Massachusetts (MA) |
| CMN | Blue shield(BS) of Northeastern New York (NeNY) |
| CMO | Unassigned Prefix |
| CMP | BCBS of Minnesota (MN) |
| CMQ | Regence BCBS |
| CMR | BCBS of Illinois (IL) |
| CMS | BCBS of Massachusetts (MA) |
| CMT | Anthem BCBS of Ohio (OH) |
| CMU | Highmark BCBS of Pennsylvania (PA) |
| CMV | Blue Shield (BS) of California |
| CMW | Wellmark |
| CMX | Excellus BCBS of New York (NY) |
| CMY | Blue Cross (BC) of Idaho (ID) |
| CMZ | Anthem BCBS of Ohio (OH) |
| CAN | Unassigned Prefix |
| CNB | Anthem BCBS of Ohio (OH) |
| CNC | BCBS of Texas (TX) |
| CND | Unassigned Prefix |
| CNE | Wellmark |
| CNF | Wellmark |
| CNG | Highmark BCBS of Pennsylvania (PA) |
| CNH | Anthem BCBS of Ohio (OH) |
| CNI | BCBS of Texas (TX) |
| CNJ | BCBS of South Carolina (SC) / Southcarolinablues |
| CNK | Wellmark |
| CNL | BCBS of Illinois (IL) |
| CNM | Highmark BCBS of Pennsylvania (PA) |
| CNN | Unassigned Prefix |
| CNO | Unassigned Prefix |
| CNP | Unassigned Prefix |
| CNQ | Unassigned Prefix |
| CNR | Carefirst BCBS of Maryland (MD)/District of Columbia (DC) and Northern Virginia (VA) |
| CNS | Unassigned Prefix |
| CNT | BCBS of Illinois (IL) |
| CNU | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CNV | BCBS of Illinois (IL) |
| CNW | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CNX | BCBS of Minnesota (MN) |
| CNY | Anthem BCBS of Virginia (VA) |
| CNZ | BCBS of Illinois (IL) |
| COA | Capital Blue Cross of Pennsylvania (PA) |
| COB | BCBS of Texas (TX) |
| COC | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| COD | Anthem BCBS of Ohio (OH) |
| COE | Unassigned Prefix |
| COF | Unassigned Prefix |
| COG | Anthem BCBS of Colorado (CO) |
| COH | Unassigned Prefix |
| COI | Unassigned Prefix |
| COJ | BCBS of Alabama (AL) |
| COK | Unassigned Prefix |
| COL | Unassigned Prefix |
| COM | BCBS of Alabama (AL) |
| CON | BCBS of Massachusetts (MA) |
| COO | BCBS of Minnesota (MN) |
| COP | BCBS of Alabama (AL) |
| COQ | Unassigned Prefix |
| COR | Unassigned Prefix |
| COS | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| COT | Blue Cross (BC) of Idaho (ID) |
| COU | Unassigned Prefix |
| COV | BCBS of Arizona (AZ) |
| COW | Unassigned Prefix |
| COX | Blue Shield (BS) of California |
| COY | Capital Blue Cross of Pennsylvania (PA) |
| COZ | Unassigned Prefix |
| CPA | BCBS of Minnesota (MN) |
| CPB | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CPC | BCBS of Alabama (AL) |
| CPD | BCBS of Massachusetts (MA) |
| CPE | BCBS of Illinois (IL) |
| CPF | BCBS of North Carolina (NC) |
| CPG | Blue shield(BS) of Northeastern New York (NeNY) |
| CPH | BCBS of Illinois (IL) |
| CPI | Unassigned Prefix |
| CPJ | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CPK | Regence BCBS |
| CPL | BCBS of Kansas City |
| CPM | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CPN | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CPO | Unassigned Prefix |
| CPP | Wellmark |
| CPQ | Anthem Blue Cross(BC) of California (CA) |
| CPR BCBS Prefix | Anthem Blue Cross(BC) of California (CA) |
| CPS | BCBS of Alabama (AL) |
| CPT | Anthem Blue Cross(BC) of California (CA) |
| CPU | BCBS of Nebraska (NE) |
| CPV | Anthem BCBS of Georgia (GA) |
| CPW | Wellmark |
| CPX | Unassigned Prefix |
| CPY | BCBS of Illinois (IL) |
| CPZ | Blue shield(BS) of Northeastern New York (NeNY) |
| CQA | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CQB | Anthem Blue Cross(BC) of California (CA) |
| CQC | Unassigned Prefix |
| CQD | Unassigned Prefix |
| CQE | Anthem BCBS of Missouri (MO) |
| CQF | Unassigned Prefix |
| CQG | Unassigned Prefix |
| CQH | Regence BCBS |
| CQI | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CQJ | BCBS of Texas (TX) |
| CQK | Blue Shield (BS) of California |
| CQL | Unassigned Prefix |
| CQM BCBS Prefix | Highmark BCBS of Pennsylvania (PA) |
| CQN | Blue Shield (BS) of California |
| CQO | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CQP | Unassigned Prefix |
| CQQ | Anthem BCBS of Colorado (CO) |
| CQR | Unassigned Prefix |
| CQS | BCBS of Western New York (WNY) |
| CQT | Unassigned Prefix |
| CQU | Unassigned Prefix |
| CQV | Wellmark |
| CQW | Unassigned Prefix |
| CQX | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CQY | Wellmark |
| CQZ | Unassigned Prefix |
| CRA | Capital Blue Cross of Pennsylvania (PA) |
| CRB | BCBS of Minnesota (MN) |
| CRC | Capital Blue Cross of Pennsylvania (PA) |
| CRD | Unassigned Prefix |
| CRE | Blue Shield (BS) of California |
| CRF | BCBS of North Carolina (NC) |
| CRG | BCBS of Texas (TX) |
| CRH | BCBS Blue Care Network Michigan (MI) |
| CRI | Anthem BCBS of Ohio (OH) |
| CRJ | Unassigned Prefix |
| CRK | BCBS of Texas (TX) |
| CRL | Excellus BCBS of New York (NY) |
| CRM | BCBS of Illinois (IL) |
| CRN | BCBS of North Carolina (NC) |
| CRO | Anthem BCBS of Virginia (VA) |
| CRP | BCBS of Illinois (IL) |
| CRQ | Anthem BCBS of Wisconsin (WI) |
| CRR | Anthem BCBS of Ohio (OH) |
| CRS | Premera BCBS of Alaska (AK) |
| CRT | Unassigned Prefix |
| CRU | BCBS of Western New York (WNY) |
| CRV | Unassigned Prefix |
| CRW | Anthem Blue Cross(BC) of California (CA) |
| CRX | BCBS of North Carolina (NC) |
| CRY | BCBS of Tennessee (TN) |
| CRZ | BCBS of Texas (TX) |
| CSA | BCBS of Alabama (AL) |
| CSB | BCBS of Illinois (IL) |
| CSC | Florida (FL) Blue |
| CSD | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CSE | Unassigned Prefix |
| CSF | Anthem BCBS of Colorado (CO) |
| CSG | Anthem BCBS of Indiana (IN) |
| CSH | Anthem BCBS of Georgia (GA) |
| CSI | BCBS of Kansas City |
| CSJ | Anthem BCBS of Missouri (MO) |
| CSK | Wellmark |
| CSL | Horizon BCBS of New Jersey (NJ) |
| CSM | Arkansas (AR) Blue Cross |
| CSN | Unassigned Prefix |
| CSO | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CSP | Excellus BCBS of New York (NY) |
| CSQ | Anthem BCBS of Missouri (MO) |
| CSR | Blue Shield (BS) of California |
| CSS | Anthem BCBS of Colorado (CO) |
| CST | Anthem BCBS of Colorado (CO) |
| CSU | Regence BCBS |
| CSV | Anthem BCBS of Virginia (VA) |
| CSW | Unassigned Prefix |
| CSX | Wellmark |
| CSY | Unassigned Prefix |
| CSZ | BCBS of South Carolina (SC) / Southcarolinablues |
| CTA | BCBS of Massachusetts (MA) |
| CTB | BCBS of South Carolina (SC) / Southcarolinablues |
| CTC | BCBS of Oklahoma (OK) |
| CTD | Anthem BCBS of Indiana (IN) |
| CTE | Unassigned Prefix |
| CTF | BCBS of Minnesota (MN) |
| CTG | Anthem BCBS of Connecticut (CT) |
| CTH | BCBS of South Carolina (SC) / Southcarolinablues |
| CTI | BCBS of Massachusetts (MA) |
| CTJ | Anthem BCBS of Indiana (IN) |
| CTK | Capital Blue Cross of Pennsylvania (PA) |
| CTL | BCBS of Illinois (IL) |
| CTM | Blue Cross (BC) of Idaho (ID) |
| CTN | Unassigned Prefix |
| CTO | Blue Shield (BS) of California |
| CTP | Unassigned Prefix |
| CTQ | BCBS of Western New York (WNY) |
| CTR | Anthem BCBS of Indiana (IN) |
| CTS | BCBS of Nebraska (NE) |
| CTT | Premera BCBS of Alaska (AK) |
| CTU | Blue Shield (BS) of California |
| CTV | Unassigned Prefix |
| CTW | Premera BCBS of Alaska (AK) |
| CTX | Blue Shield (BS) of California |
| CTY | BCBS of Illinois (IL) |
| CTZ | BCBS of Arizona (AZ) |
| CUA | Unassigned Prefix |
| CUB | Excellus BCBS of New York (NY) |
| CUC | Unassigned Prefix |
| CUD | BCBS of Massachusetts (MA) |
| CUE | Unassigned Prefix |
| CUF | Blue Shield (BS) of California |
| CUG | Wellmark |
| CUH | Anthem BCBS of Colorado (CO) |
| CUI | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CUJ | Unassigned Prefix |
| CUK | BCBS of Alabama (AL) |
| CUL | Unassigned Prefix |
| CUM | Unassigned Prefix |
| CUN | Highmark BCBS of Pennsylvania (PA) |
| CUO | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CUP | Wellmark |
| CUQ | Blue Shield (BS) of California |
| CUR | BCBS of Western New York (WNY) |
| CUS | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CUT | BCBS of Illinois (IL) |
| CUU | BCBS of Texas (TX) |
| CUV | BCBS of Illinois (IL) |
| CUW | Wellmark |
| CUX | Regence BCBS |
| CUY | Regence BCBS |
| CUZ | Anthem BCBS of Ohio (OH) |
| CVA | Anthem BCBS of Indiana (IN) |
| CVB | Florida (FL) Blue |
| CVC | BCBS of Illinois (IL) |
| CVD | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CVE | Anthem BCBS of Indiana (IN) |
| CVF | Anthem BCBS of Ohio (OH) |
| CVG | Anthem BCBS of Ohio (OH) |
| CVH | Unassigned Prefix |
| CVI | BCBS of Alabama (AL) |
| CVJ | Florida (FL) Blue |
| CVK | Florida (FL) Blue |
| CVL | Regence BCBS |
| CVM | Anthem BCBS of Wisconsin (WI) |
| CVN | Anthem BCBS of Connecticut (CT) |
| CVO | Anthem BCBS of Virginia (VA) |
| CVP | Anthem BCBS of Ohio (OH) |
| CVQ | Unassigned Prefix |
| CVR | Anthem BCBS of Indiana (IN) |
| CVS | Wellmark |
| CVT | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CVU | Anthem BCBS of Virginia (VA) |
| CVV | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CVW | Unassigned Prefix |
| CVX | BCBS of Illinois (IL) |
| CVY | Anthem BCBS of Ohio (OH) |
| CVZ | Wellmark |
| CWA | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CWB | Anthem BCBS of Ohio (OH) |
| CWC | Unassigned Prefix |
| CWD | Wellmark |
| CWE | BCBS Blue Care Network Michigan (MI) |
| CWF | Blue Cross (BC) of Idaho (ID) |
| CWG | Anthem BCBS of Ohio (OH) |
| CWH | Anthem BCBS of Missouri (MO) |
| CWI | Blue Shield (BS) of California |
| CWJ | Unassigned Prefix |
| CWK | BCBS of Massachusetts (MA) |
| CWL | Unassigned Prefix |
| CWM | Highmark BCBS of Pennsylvania (PA) |
| CWN | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CWO | BCBS of Massachusetts (MA) |
| CWP | BCBS of Texas (TX) |
| CWQ | Anthem BCBS of Ohio (OH) |
| CWR | Anthem BCBS of Wisconsin (WI) |
| CWS | Anthem BCBS of Georgia (GA) |
| CWT | BCBS of Texas (TX) |
| CWU | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CWV | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CWW | Wellmark |
| CWX | Anthem BCBS of Missouri (MO) |
| CWY | Wellmark |
| CWZ | Empire BCBS of New York (NY) |
| CXA | Unassigned Prefix |
| CXB | Blue Cross (BC) of Idaho (ID) |
| CXC | BCBS of Rhode Islanad (RI) |
| CXD | BCBS of Illinois (IL) |
| CXE | Unassigned Prefix |
| CXF | Premera BCBS of Alaska (AK) |
| CXG | BCBS of Minnesota (MN) |
| CXH | BCBS of Minnesota (MN) |
| CXI | BCBS of Nebraska (NE) |
| CXJ | Excellus BCBS of New York (NY) |
| CXK | BCBS of Texas (TX) |
| CXL | Unassigned Prefix |
| CXM | Unassigned Prefix |
| CXN | Unassigned Prefix |
| CXO | Arkansas (AR) Blue Cross |
| CXP | BCBS of Texas (TX) |
| CXQ | Wellmark |
| CXR | BCBS of Rhode Islanad (RI) |
| CXS | Anthem BCBS of Georgia (GA) |
| CXT | BCBS of Illinois (IL) |
| CXU | Unassigned Prefix |
| CXV | Unassigned Prefix |
| CXW | Unassigned Prefix |
| CXX | Blue Shield (BS) of California |
| CXY | Unassigned Prefix |
| CXZ | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CYA | BCBS of Illinois (IL) |
| CYB | Blue Shield (BS) of California |
| CYC | BCBS of Illinois (IL) |
| CYD | Unassigned Prefix |
| CYE | Regence BCBS |
| CYF | Unassigned Prefix |
| CYG | Florida (FL) Blue |
| CYH | Unassigned Prefix |
| CYI | BCBS of Massachusetts (MA) |
| CYJ | Anthem BCBS of Georgia (GA) |
| CYK | Florida (FL) Blue |
| CYL | BCBS of Illinois (IL) |
| CYM | Unassigned Prefix |
| CYN | Unassigned Prefix |
| CYO | BCBS of Massachusetts (MA) |
| CYP | BCBS of Illinois (IL) |
| CYQ | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CYR | BCBS of Texas (TX) |
| CYS BCBS Prefix | BCBS of Illinois (IL) |
| CYT | Anthem BCBS of Georgia (GA) |
| CYU | Empire BCBS of New York (NY) |
| CYV | Regence BCBS |
| CYW | Unassigned Prefix |
| CYX | BCBS of North Carolina (NC) |
| CYY | BCBS of North Carolina (NC) |
| CYZ | Regence BCBS |
| CZA | Anthem BCBS of Kentucky (KY) |
| CZB | Anthem BCBS of Indiana (IN) |
| CZC | Anthem BCBS of Connecticut (CT) |
| CZD | Unassigned Prefix |
| CZE | BCBS of Texas (TX) |
| CZF | Unassigned Prefix |
| CZG | Carefirst BCBS of Maryland (MD)/ District of Columbia (DC) and Northern Virginia (VA) |
| CZH | Anthem BCBS of Connecticut (CT) |
| CZI | Blue Shield (BS) of California |
| CZJ | Unassigned Prefix |
| CZK | Anthem BCBS of Virginia (VA) |
| CZL | Unassigned Prefix |
| CZM | Unassigned Prefix |
| CZN | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CZO | Unassigned Prefix |
| CZP | Anthem BCBS of Ohio (OH) |
| CZQ | Anthem BCBS of Ohio (OH) |
| CZR | Wellmark |
| CZS | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CZT | Anthem BCBS of Connecticut (CT) |
| CZU | Anthem Blue Cross(BC) of California (CA) |
| CZV | Independence Blue Cross(BC) of Philadelphia(Phi) and Southeastern Pennsylvania(PA) |
| CZW | BCBS of Minnesota (MN) |
| CZX | Unassigned Prefix |
| CZY | BCBS of North Carolina (NC) |
| CZZ | Unassigned Prefix |
