| IAA | Anthem BCBS of Wisconsin |
| IAB | Wellmark BCBS |
| IAC | Regence BCBS |
| IAD | Anthem BCBS of Indiana |
| IAE | BCBS of Michigan |
| IAF | BCBS of Western New York |
| IAG | Anthem BCBS of Virginia |
| IAH | Wellmark BCBS |
| IAI | BCBS of South Carolina |
| IAJ | CareFirst BCBS |
| IAK | Blue Shield of California |
| IAL | Wellmark BCBS |
| IAM | Blue Shield of California |
| IAN | No Prefix Assigned |
| IAO | BCBS of Western New York |
| IAP | Wellmark BCBS |
| IAQ | BCBS of Nebraska |
| IAR | BCBS of Alabama |
| IAS | BCBS of Massachusetts |
| IAT | Empire BCBS |
| IAU | BCBS of Nebraska |
| IAV | Wellmark BCBS |
| IAW | Wellmark BCBS |
| IAX | Wellmark BCBS |
| IAY | BCBS of South Carolina |
| IAZ | Wellmark BCBS |
| IBA | BCBS of Illinois |
| IBB | Horizon BCBS of New Jersey |
| IBC | Anthem BCBS of Wisconsin |
| IBD | Anthem BCBS of Wisconsin |
| IBE | BCBS of Illinois |
| IBF | Wellmark BCBS |
| IBG | BCBS of Illinois |
| IBH | BCBS of Alabama |
| IBI | Wellmark BCBS |
| IBJ | BCBS of Michigan |
| IBK | Blue Cross of California |
| IBL | Independence Blue Cross FOC |
| IBM | Blue Shield of California |
| IBN | No Prefix Assigned |
| IBO | Independence Blue Cross FOC |
| IBP | Wellmark BCBS |
| IBQ | Regence BCBS |
| IBR | BCBS of Michigan |
| IBS | Anthem BCBS of Georgia |
| IBT | BCBS of Illinois |
| IBU | BCBS of Alabama |
| IBV | BCBS of Massachusetts |
| IBW | BCBS of Illinois |
| IBX | Blue Cross of California |
| IBY | No Prefix Assigned |
| IBZ | Regence BCBS |
| ICA | CareFirst BCBS |
| ICB | BCBS of Illinois |
| ICC | Anthem BCBS of Colorado |
| ICD | CareFirst BCBS |
| ICE | CareFirst BCBS |
| ICF | CareFirst BCBS |
| ICG | BCBS of South Carolina |
| ICH | Anthem BCBS of Virginia |
| ICI | BCBS of South Carolina |
| ICJ | Anthem BCBS of Georgia |
| ICK | CareFirst BCBS |
| ICL | CareFirst BCBS |
| ICM | Blue Shield of California |
| ICN | Anthem BCBS of Georgia |
| ICO | BCBS of North Carolina |
| ICP | Anthem BCBS of Georgia |
| ICQ | Anthem BCBS of Virginia |
| ICR | Anthem BCBS of Ohio |
| ICS | Anthem BCBS of Missouri |
| ICT | BCBS of Western New York |
| ICU | Regence BCBS |
| ICV | BCBS of Michigan |
| ICW | BCBS of Massachusetts |
| ICX | Anthem BCBS of Wisconsin |
| ICY | Anthem BCBS of Ohio |
| ICZ | CareFirst BCBS |
| IDA | Blue Cross of Idaho |
| IDB | BCBS of South Carolina |
| IDC | Blue Cross of California |
| IDD | Anthem BCBS of Virginia |
| IDE | Blue Cross of Idaho |
| IDF | Blue Cross of Idaho |
| IDG | CareFirst BCBS |
| IDH | Highmark BCBS of Pennsylvania |
| IDI | Blue Shield of California |
| IDJ | Anthem BCBS of Virginia |
| IDK | Empire BCBS |
| IDL | Blue Cross of Idaho |
| IDM | Blue Cross of Idaho |
| IDN | Blue Cross of Idaho |
| IDO | BCBS of South Carolina |
| IDP | Blue Cross of Idaho |
| IDQ | Anthem BCBS of Virginia |
| IDR | Blue Cross of California |
| IDS | BCBS of South Carolina |
| IDT | Anthem BCBS of Virginia |
| IDU | BCBS of South Carolina |
| IDV | Blue Cross of Idaho |
| IDW | No Prefix Assigned |
| IDX | BCBS of Illinois |
| IDY | BCBS of South Carolina |
| IDZ | Wellmark BCBS |
| IEA | Regence BCBS |
| IEB | Anthem BCBS of Indiana |
| IEC | Blue Shield of California |
| IED | Anthem BCBS of Indiana |
| IEE | No Prefix Assigned |
| IEF | BCBS of Massachusetts |
| IEG | CareFirst BCBS |
| IEH | Premera Blue Cross |
| IEI | Independence Blue Cross FOC |
| IEJ | BCBS of South Carolina |
| IEK | CareFirst BCBS |
| IEL | BCBS of Illinois |
| IEM | Blue Shield of Northeastern New York |
| IEN | Blue Cross of California |
| IEO | BCBS of South Carolina |
| IEP | BCBS of Louisiana |
| IEQ | Empire BCBS |
| IER | Anthem BCBS of Virginia |
| IES | BCBS of Texas |
| IET | Anthem BCBS of Connecticut |
| IEU | BCBS of Louisiana |
| IEV | BCBS of Alabama |
| IEW | BCBS of Illinois |
| IEX | BCBS of Michigan |
| IEY | BCBS of South Carolina |
| IEZ | CareFirst BCBS |
| IFA | Anthem BCBS of Georgia |
| IFB | Wellmark BCBS |
| IFC | BCBS of Western New York |
| IFD | Regence BCBS |
| IFE | Anthem BCBS of Georgia |
| IFF | Wellmark BCBS |
| IFG | No Prefix Assigned |
| IFH | Highmark BCBS of Pennsylvania |
| IFI | Highmark BCBS of Pennsylvania |
| IFJ | Highmark BCBS of Pennsylvania |
| IFK | Highmark BCBS of Pennsylvania |
| IFL | Regence BCBS |
| IFM | Blue Cross of California |
| IFN | Highmark BCBS of Pennsylvania |
| IFO | Highmark BCBS of Pennsylvania |
| IFP | Anthem BCBS of Nevada |
| IFQ | CareFirst BCBS |
| IFR | Anthem BCBS of Kentucky |
| IFS | BCBS of Kansas City |
| IFT | Highmark BCBS of Pennsylvania |
| IFU | Highmark BCBS of Pennsylvania |
| IFV | Highmark BCBS of Pennsylvania |
| IFW | Highmark BCBS of Pennsylvania |
| IFX | Anthem BCBS of Ohio |
| IFY | CareFirst BCBS |
| IFZ | BCBS of South Carolina |
| IGA | Independence Blue Cross FOC |
| IGB | Anthem BCBS of Georgia |
| IGC | CareFirst BCBS |
| IGD | Wellmark BCBS |
| IGE | BCBS of Alabama |
| IGF | Blue Shield of California |
| IGG | Blue Shield of California |
| IGH | Independence Blue Cross FOC |
| IGI | Wellmark BCBS |
| IGJ | Independence Blue Cross FOC |
| IGK | Highmark BCBS of Pennsylvania |
| IGL | Highmark BCBS of Pennsylvania |
| IGM | CareFirst BCBS |
| IGN | Highmark BCBS of Pennsylvania |
| IGO | BCBS of Western New York |
| IGP | Wellmark BCBS |
| IGQ | Highmark BCBS of Pennsylvania |
| IGR | Empire BCBS |
| IGS | BCBS of Alabama |
| IGT | Blue Shield of California |
| IGU | BCBS of Louisiana |
| IGV | Highmark BCBS of Pennsylvania |
| IGW | CareFirst BCBS |
| IGX | CareFirst BCBS |
| IGY | CareFirst BCBS |
| IGZ | Highmark BCBS of Pennsylvania |
| IHA | Blue Shield of California |
| IHB | Wellmark BCBS |
| IHC | CareFirst BCBS |
| IHD | BCBS of Nebraska |
| IHE | Anthem BCBS of Ohio |
| IHF | Empire BCBS |
| IHG | Anthem BCBS of Georgia |
| IHH | BCBS of Alabama |
| IHI | Highmark BCBS of Pennsylvania |
| IHJ | Empire BCBS |
| IHK | Highmark BCBS of Pennsylvania |
| IHL | Highmark BCBS of Pennsylvania |
| IHM | Highmark BCBS of Pennsylvania |
| IHN | Blue Shield of California |
| IHO | BCBS of South Carolina |
| IHP | CareFirst BCBS |
| IHQ | BCBS of South Carolina |
| IHR | Blue Shield of California |
| IHS | BCBS of Massachusetts |
| IHT | BCBS of Alabama |
| IHU | No Prefix Assigned |
| IHV | Anthem BCBS of Georgia |
| IHW | Blue Shield of California |
| IHX | Anthem BCBS of Colorado |
| IHY | Anthem BCBS of Georgia |
| IHZ | Blue Cross of California |
| IIA | Blue Shield of California |
| IIB | BCBS of Michigan |
| IIC | Horizon BCBS of New Jersey |
| IID | Blue Cross of Idaho |
| IIE | Highmark BCBS of Pennsylvania |
| IIF | Anthem BCBS of Georgia |
| IIG | Highmark BCBS of Pennsylvania |
| IIH | Regence BCBS |
| III | BCBS of Tennessee Commercial |
| IIJ | Highmark BCBS of Pennsylvania |
| IIK | Highmark BCBS of Pennsylvania |
| IIL | Highmark BCBS of Pennsylvania |
| IIM | Highmark BCBS of Pennsylvania |
| IIN | BCBS of Massachusetts |
| IIO | No Prefix Assigned |
| IIP | BCBS of Western New York |
| IIQ | BCBS of South Carolina |
| IIR | BCBS of South Carolina |
| IIS | BCBS of Michigan |
| IIT | BCBS of Illinois |
| IIU | Independence Blue Cross FOC |
| IIV | BCBS of South Carolina |
| IIW | Blue Shield of California |
| IIX | Blue Cross of Idaho |
| IIY | BCBS of South Carolina |
| IIZ | BCBS of South Carolina |
| IJA | Anthem BCBS of Wisconsin |
| IJB | Anthem BCBS of Ohio |
| IJC | BCBS of South Carolina |
| IJD | Anthem BCBS of New Hampshire |
| IJE | BCBS of Western New York |
| IJF | Anthem BCBS of Georgia |
| IJG | Anthem BCBS of Georgia |
| IJH | Anthem BCBS of Georgia |
| IJI | Anthem BCBS of Georgia |
| IJJ | Anthem BCBS of Georgia |
| IJK | Anthem BCBS of Georgia |
| IJL | Anthem BCBS of Georgia |
| IJM | BCBS of South Carolina |
| IJN | BCBS of South Carolina |
| IJO | BCBS of South Carolina |
| IJP | BCBS of South Carolina |
| IJQ | Anthem BCBS of Georgia |
| IJR | Blue Cross of Idaho |
| IJS | Anthem BCBS of Wisconsin |
| IJT | Anthem BCBS of Georgia |
| IJU | BCBS of Texas |
| IJV | Anthem BCBS of Georgia |
| IJW | Horizon BCBS of New Jersey |
| IJX | Anthem BCBS of Georgia |
| IJY | Capital Blue Cross |
| IJZ | BCBS of South Carolina |
| IKA | Anthem BCBS of Kentucky |
| IKB | Anthem BCBS of Virginia |
| IKC | Anthem BCBS of Virginia |
| IKD | Wellmark BCBS |
| IKE | Independence Blue Cross FOC |
| IKF | Independence Blue Cross FOC |
| IKG | Anthem BCBS of Georgia |
| IKH | Wellmark BCBS |
| IKI | BCBS of South Carolina |
| IKJ | BCBS of South Carolina |
| IKK | BCBS of Michigan |
| IKL | Anthem BCBS of Virginia |
| IKM | Independence Blue Cross FOC |
| IKN | No Prefix Assigned |
| IKO | Highmark BCBS of Pennsylvania |
| IKP | No Prefix Assigned |
| IKQ | Wellmark BCBS |
| IKR | Anthem BCBS of Missouri |
| IKS | Blue Shield of California |
| IKT | Anthem BCBS of Kentucky |
| IKU | Anthem BCBS of Georgia |
| IKV | BCBS of Michigan |
| IKW | Anthem BCBS of Georgia |
| IKX | BCBS of Michigan |
| IKY | BCBS of South Carolina |
| IKZ | No Prefix Assigned |
| ILA | Empire BCBS |
| ILB | BCBS of Massachusetts |
| ILC | Wellmark BCBS |
| ILD | BCBS of Michigan |
| ILE | Wellmark BCBS |
| ILF | BCBS of Alabama |
| ILG | Blue Shield of California |
| ILH | Blue Cross of California |
| ILI | Blue Shield of California |
| ILJ | Anthem BCBS of Wisconsin |
| ILK | Regence Group Administrators – Washington |
| ILL | Blue Cross of California |
| ILM | Blue Cross of California |
| ILN | BCBS of Tennessee Commercial |
| ILO | Anthem BCBS of Wisconsin |
| ILP | BCBS of South Carolina |
| ILQ | Blue Cross of California |
| ILR | No Prefix Assigned |
| ILS | Premera Blue Cross |
| ILT | BCBS of Illinois |
| ILU | Blue Cross of California |
| ILV | BCBS of Alabama |
| ILW | Blue Shield of California |
| ILX | BCBS of Alabama |
| ILY | Blue Cross of California |
| ILZ | BCBS of Michigan |
| IMA | Excellus BCBS |
| IMB | BCBS of Massachusetts |
| IMC | Premera Blue Cross |
| IMD | No Prefix Assigned |
| IME | Highmark BCBS of Pennsylvania |
| IMF | No Prefix Assigned |
| IMG | Blue Cross of California |
| IMH | Anthem BCBS of Colorado |
| IMI | Wellmark BCBS |
| IMJ | Anthem BCBS of Missouri |
| IMK | Anthem BCBS of Maine |
| IML | No Prefix Assigned |
| IMM | BCBS of Western New York |
| IMN | No Prefix Assigned |
| IMO | Blue Cross of California |
| IMP | BCBS of Alabama |
| IMQ | BCBS of Tennessee Commercial |
| IMR | BCBS of Alabama |
| IMS | Anthem BCBS of Kentucky |
| IMT | Wellmark BCBS |
| IMU | BCBS of South Carolina |
| IMV | BCBS of Massachusetts |
| IMW | Anthem BCBS of Ohio |
| IMX | Anthem BCBS of Missouri |
| IMY | BCBS of South Carolina |
| IMZ | Wellmark BCBS |
| INA | Anthem BCBS of Kentucky |
| INB | Premera Blue Cross |
| INC | Blue Cross of California |
| IND | Anthem BCBS of Virginia |
| INE | BCBS of South Carolina |
| INF | Blue Shield of California |
| ING | Anthem BCBS of Ohio |
| INH | No Prefix Assigned |
| INI | Highmark BCBS of Pennsylvania |
| INJ | Anthem BCBS of Kentucky |
| INK | Blue Cross of California |
| INL | BCBS of Tennessee Commercial |
| INM | No Prefix Assigned |
| INN | BCBS of Nebraska |
| INO | Blue Shield of California |
| INP | BCBS of North Carolina |
| INQ | Regence Group Administrators – Washington |
| INR | Anthem BCBS of Indiana |
| INS | Wellmark BCBS |
| INT | Anthem BCBS of Virginia |
| INU | BCBS of South Carolina |
| INV | BCBS of South Carolina |
| INW | Independence Blue Cross FOC |
| INX | BCBS of North Carolina |
| INY | Blue Cross of California |
| INZ | Blue Shield of California |
| IOA | BCBS of Arizona |
| IOB | BCBS of Tennessee Commercial |
| IOC | Blue Shield of California |
| IOD | BCBS of Michigan |
| IOE | Empire BCBS |
| IOF | Blue Shield of California |
| IOG | Blue Shield of Northeastern New York |
| IOH | No Prefix Assigned |
| IOI | BCBS of Michigan |
| IOJ | BCBS of Michigan |
| IOK | Anthem BCBS of Virginia |
| IOL | BCBS of Michigan |
| IOM | BCBS of Michigan |
| ION | BCBS of Florida |
| IOO | BCBS of Michigan |
| IOP | BCBS of Western New York |
| IOQ | BCBS of Michigan |
| IOR | BCBS of South Carolina |
| IOS | BCBS of North Carolina |
| IOT | Highmark BCBS of Pennsylvania |
| IOU | BCBS of South Carolina |
| IOV | BCBS of South Carolina |
| IOW | No Prefix Assigned |
| IOX | Anthem BCBS of Ohio |
| IOY | BCBS of South Carolina |
| IOZ | Blue Shield of California |
| IPA | Anthem BCBS of Virginia |
| IPB | Highmark BCBS of Pennsylvania |
| IPC | No Prefix Assigned |
| IPD | Highmark BCBS of Pennsylvania |
| IPE | Blue Shield of California |
| IPF | Wellmark BCBS |
| IPG | Anthem BCBS of Virginia |
| IPH | BCBS of Kansas |
| IPI | Anthem BCBS of Georgia |
| IPJ | Anthem BCBS of Georgia |
| IPK | Blue Shield of California |
| IPL | No Prefix Assigned |
| IPM | Highmark BCBS of Pennsylvania |
| IPN | Highmark BCBS of Pennsylvania |
| IPO | No Prefix Assigned |
| IPP | BCBS of Alabama |
| IPQ | Anthem BCBS of Ohio |
| IPR | Wellmark BCBS |
| IPS | Blue Shield of California |
| IPT | BCBS of Illinois |
| IPU | Blue Cross of Idaho |
| IPV | BCBS of Michigan |
| IPW | Regence Blue Shield of Idaho |
| IPX | Wellmark BCBS |
| IPY | BCBS of Western New York |
| IPZ | BCBS of Rhode Island |
| IQA | Premera Blue Cross |
| IQB | Anthem BCBS of Georgia |
| IQC | Capital Blue Cross |
| IQD | Anthem BCBS of Georgia |
| IQE | BCBS of Tennessee Commercial |
| IQF | BCBS of Tennessee Commercial |
| IQG | Anthem BCBS of Indiana |
| IQH | Anthem BCBS of Kentucky |
| IQI | Anthem BCBS of Missouri |
| IQJ | Anthem BCBS of Virginia |
| IQK | Anthem BCBS of Georgia |
| IQL | Blue Cross of California |
| IQM | Anthem BCBS of Georgia |
| IQN | BCBS of South Carolina |
| IQO | Blue Cross of California |
| IQP | Anthem BCBS of Georgia |
| IQQ | Blue Cross of California |
| IQR | Anthem BCBS of Georgia |
| IQS | Independence Blue Cross FOC |
| IQT | Anthem BCBS of Ohio |
| IQU | BCBS of Michigan |
| IQV | Blue Cross of California |
| IQW | Blue Cross of California |
| IQX | Blue Cross of California |
| IQY | BCBS of South Carolina |
| IQZ | Horizon BCBS of New Jersey |
| IRA | Horizon BCBS of New Jersey |
| IRB | BCBS of Massachusetts |
| IRC | Anthem BCBS of Colorado |
| IRD | BCBS of Massachusetts |
| IRE | Independence Blue Cross FOC |
| IRF | Blue Cross of California |
| IRG | BCBS of South Carolina |
| IRH | Anthem BCBS of Georgia |
| IRI | BCBS of Rhode Island |
| IRJ | BCBS of South Carolina |
| IRK | BCBS of Alabama |
| IRL | No Prefix Assigned |
| IRM | BCBS of Kansas City |
| IRN | No Prefix Assigned |
| IRO | Anthem BCBS of Ohio |
| IRP | BCBS of Florida |
| IRQ | BCBS of South Carolina |
| IRR | Anthem BCBS of Ohio |
| IRS | BCBS of Florida |
| IRT | Wellmark BCBS |
| IRU | Anthem BCBS of Connecticut |
| IRV | BCBS of Massachusetts |
| IRW | Blue Shield of California |
| IRX | BCBS of Massachusetts |
| IRY | Independence Blue Cross FOC |
| IRZ | Blue Cross of California |
| ISA | Anthem BCBS of Ohio |
| ISB | Premera Blue Cross |
| ISC | Horizon BCBS of New Jersey |
| ISD | BCBS of Arizona |
| ISE | Anthem BCBS of Virginia |
| ISF | BCBS of Arizona |
| ISG | No Prefix Assigned |
| ISH | CareFirst BCBS |
| ISI | Blue Shield of California |
| ISJ | Independence Blue Cross FOC |
| ISK | CareFirst BCBS |
| ISL | Wellmark BCBS |
| ISM | Highmark BCBS of Pennsylvania |
| ISN | Blue Cross of Idaho |
| ISO | BCBS of Massachusetts |
| ISP | Anthem BCBS of Wisconsin |
| ISQ | BCBS of Kansas City |
| ISR | CareFirst BCBS |
| ISS | Horizon BCBS of New Jersey |
| IST | Anthem BCBS of Ohio |
| ISU | Blue Cross of Idaho |
| ISV | BCBS of Michigan |
| ISW | Blue Cross of Idaho |
| ISX | Wellmark BCBS |
| ISY | No Prefix Assigned |
| ISZ | Blue Cross of Idaho |
| ITA | CareFirst BCBS |
| ITB | Wellmark BCBS |
| ITC | BCBS of Massachusetts |
| ITD | Independence Blue Cross FOC |
| ITE | BCBS of North Carolina |
| ITF | BCBS of Michigan |
| ITG | Anthem BCBS of Georgia |
| ITH | Capital Blue Cross |
| ITI | Anthem BCBS of Georgia |
| ITJ | BCBS of Tennessee Commercial |
| ITK | CareFirst BCBS |
| ITL | No Prefix Assigned |
| ITM | BCBS of Michigan |
| ITN | Blue Shield of California |
| ITO | Blue Shield of Northeastern New York |
| ITP | Anthem BCBS of Ohio |
| ITQ | Wellmark BCBS |
| ITR | Empire BCBS |
| ITS | BCBS of Arkansas |
| ITT | Blue Cross of California |
| ITU | Regence BCBS |
| ITV | Anthem BCBS of Georgia |
| ITW | BCBS of Illinois |
| ITX | Regence BCBS |
| ITY | Independence Blue Cross FOC |
| ITZ | Anthem BCBS of Georgia |
| IUA | Wellmark BCBS |
| IUB | Anthem BCBS of Connecticut |
| IUC | Anthem BCBS of Ohio |
| IUD | No Prefix Assigned |
| IUE | Empire BCBS |
| IUF | Anthem BCBS of Missouri |
| IUG | Premera Blue Cross |
| IUH | BCBS of Massachusetts |
| IUI | BCBS of Rhode Island |
| IUJ | BCBS of South Carolina |
| IUK | BCBS of South Carolina |
| IUL | CareFirst BCBS |
| IUM | BCBS of Massachusetts |
| IUN | No Prefix Assigned |
| IUO | Empire BCBS |
| IUP | Anthem BCBS of Connecticut |
| IUQ | CareFirst BCBS |
| IUR | Independence Blue Cross FOC |
| IUS | Independence Blue Cross FOC |
| IUT | Anthem BCBS of Ohio |
| IUU | No Prefix Assigned |
| IUV | Regence BCBS |
| IUW | Anthem BCBS of Ohio |
| IUX | Empire BCBS |
| IUY | Anthem BCBS of Georgia |
| IUZ | Empire BCBS |
| IVA | No Prefix Assigned |
| IVB | BCBS of Michigan |
| IVC | BCBS of Kansas City |
| IVD | Highmark BCBS of Pennsylvania |
| IVE | Blue Shield of California |
| IVF | BCBS of Tennessee Commercial |
| IVG | Blue Cross of California |
| IVH | BCBS of Rhode Island |
| IVI | BCBS of South Carolina |
| IVJ | Anthem BCBS of Wisconsin |
| IVK | BCBS of Mississippi |
| IVL | BCBS of South Carolina |
| IVM | BCBS of South Carolina |
| IVN | BCBS of Tennessee Commercial |
| IVO | Horizon BCBS of New Jersey |
| IVP | BCBS of Michigan |
| IVQ | No Prefix Assigned |
| IVR | BCBS of South Carolina |
| IVS | Blue Cross of California |
| IVT | Wellmark BCBS |
| IVU | BCBS of South Carolina |
| IVV | Highmark BCBS of Pennsylvania |
| IVW | Anthem BCBS of Wisconsin |
| IVX | Anthem BCBS of Ohio |
| IVY | BCBS of Rhode Island |
| IVZ | Anthem BCBS of Ohio |
| IWA | Anthem BCBS of Ohio |
| IWB | BCBS of Nebraska |
| IWC | Anthem BCBS of Virginia |
| IWD | CareFirst BCBS |
| IWE | Wellmark BCBS |
| IWF | Empire BCBS |
| IWG | Excellus BCBS |
| IWH | CareFirst BCBS |
| IWI | Anthem BCBS of Georgia |
| IWJ | Anthem BCBS of Ohio |
| IWK | BCBS of Michigan |
| IWL | Blue Cross of California |
| IWM | Blue Shield of Northeastern New York |
| IWN | Anthem BCBS of Ohio |
| IWO | Anthem BCBS of Missouri |
| IWP | BCBS of Michigan |
| IWQ | Blue Cross of California |
| IWR | Anthem BCBS of Connecticut |
| IWS | Wellmark BCBS |
| IWT | Capital Blue Cross |
| IWU | Anthem BCBS of Virginia |
| IWV | BCBS of Kansas City |
| IWW | BCBS of Massachusetts |
| IWX | BCBS of Western New York |
| IWY | Empire BCBS |
| IWZ | BCBS of Michigan |
| IXA | BCBS of Arkansas |
| IXB | Blue Shield of California |
| IXC | Blue Shield of California |
| IXD | Blue Cross of California |
| IXE | Anthem BCBS of Ohio |
| IXF | Anthem BCBS of Indiana |
| IXG | Anthem BCBS of Indiana |
| IXH | Anthem BCBS of Indiana |
| IXI | BCBS of South Carolina |
| IXJ | Anthem BCBS of Indiana |
| IXK | Empire BCBS |
| IXL | Blue Shield of California |
| IXM | Blue Shield of California |
| IXN | Anthem BCBS of Ohio |
| IXO | Blue Shield of California |
| IXP | Anthem BCBS of Missouri |
| IXQ | BCBS of South Carolina |
| IXR | BCBS of Michigan |
| IXS | Independence Blue Cross FOC |
| IXT | Blue Cross of California |
| IXU | Independence Blue Cross FOC |
| IXV | No Prefix Assigned |
| IXW | BCBS of Michigan |
| IXX | Empire BCBS |
| IXY | Anthem BCBS of Ohio |
| IXZ | Anthem BCBS of Georgia |
| IYA | No Prefix Assigned |
| IYB | Anthem BCBS of Wisconsin |
| IYC | Independence Blue Cross FOC |
| IYD | Capital Blue Cross |
| IYE | Wellmark BCBS |
| IYF | No Prefix Assigned |
| IYG | BCBS of South Carolina |
| IYH | Anthem BCBS of Kentucky |
| IYI | BCBS of Michigan |
| IYJ | BCBS of South Carolina |
| IYK | BCBS of South Carolina |
| IYL | Blue Cross of California |
| IYM | BCBS of Minnesota |
| IYN | Premera Blue Cross |
| IYO | BCBS of Michigan |
| IYP | Anthem BCBS of Colorado |
| IYQ | BCBS of South Carolina |
| IYR | BCBS of South Carolina |
| IYS | BCBS of Rhode Island |
| IYT | Anthem BCBS of Georgia |
| IYU | BCBS of Michigan |
| IYV | BCBS of Michigan |
| IYW | Independence Blue Cross FOC |
| IYX | BCBS of Michigan |
| IYY | BCBS of Michigan |
| IYZ | BCBS of Michigan |
| IZA | BCBS of Alabama |
| IZB | Anthem BCBS of Wisconsin |
| IZC | No Prefix Assigned |
| IZD | Anthem BCBS of Georgia |
| IZE | CareFirst BCBS |
| IZF | Independence Blue Cross FOC |
| IZG | BCBS of Michigan |
| IZH | Anthem BCBS of Georgia |
| IZI | BCBS of Michigan |
| IZJ | BCBS of Michigan |
| IZK | Anthem BCBS of Ohio |
| IZL | BCBS of Michigan |
| IZM | BCBS of Michigan |
| IZN | Anthem BCBS of Georgia |
| IZO | BCBS of Michigan |
| IZP | Blue Cross of Idaho |
| IZQ | BCBS of Michigan |
| IZR | BCBS of Michigan |
| IZS | BCBS of Michigan |
| IZT | BCBS of Michigan |
| IZU | Wellmark BCBS |
| IZV | Anthem BCBS of Georgia |
| IZW | BCBS of Michigan |
| IZX | BCBS of Michigan |
| IZY | BCBS of Michigan |
| IZZ | Anthem Blue Cross of California |
| I2A | Blue Shield of California |
| I2C | Anthem BCBS of Colorado |
| I2F | Blue Cross of California |
| I2I | Blue Cross of California |
| I2P | Regence BCBS |
| I2T | Regence BCBS |
| I2V | Anthem Blue Cross of California |
| I2W | Regence BCBS |
| I3H | BCBS of Alabama |
| I3L | Capital Blue Cross |
| I3T | Anthem BCBS of Virginia |
| I3W | Regence BCBS |
| I4A | Anthem BCBS of Virginia |
