| OAA OAJ OAO OAV OAW OAX OAY OBG OBH OBK OBS OBY OBZ OCB OCC OCE OCJ OCL OCQ OCS ODC ODD ODE ODG ODH ODP ODU OEC OED OEN OEO OEP OEX OFD OFE OFI OFK OFR OGA OGB OGE OGG OGI OGP OGQ OGR OGV OGY OGZ OHQ OHW OIA OIE OIF OIH OJA OJB OJC OJD OJG OJH OJS OJU OJZ OKU OLC OLE OLF OLJ OLK OLL OLO OLP OLR OMC OMF OMJ OMM OMN OMO OMU OMW OMY ONF ONJ ONK ONM ONN ONR OOY OPC OPH OPL OPM OPN OPO OPQ OQA OQX OQY OQZ ORA ORP ORR ORW OSA OSC OSD OSF OSG OSK OSN OSP OSU OTO OTR OTV OUG OUS OVA OVB OVE OVF OVJ OVK OVS OWM OWN OWP OWV OXB OXC OXF OXS OXZ OYE OYP OYV OYZ OZH OZO OZW | Alpha Prefix not assigned or unallocated |
| OAG OHR OKR OLU OMX | Anthem Blue Cross Blue Shield of Colorado |
| OTQ OWH | Anthem Blue Cross Blue Shield of Connecticut |
| OBV OBX OGH OMI OPE OTW OWT | Anthem Blue Cross Blue Shield of Georgia |
| OAS OFA OHH ONC ONE ONI ONW ONX ONZ OTE OTF OVP | Anthem Blue Cross Blue Shield of Indiana |
| OAP OGN OHJ ORC | Anthem Blue Cross Blue Shield of Kentucky |
| OFX OJM OMK ONA ONP ORH OZA OZK OZX | Anthem Blue Cross Blue Shield of Missouri |
| OAC OAE OCP OCU ODB OFH OGD OHB OHO OHP OHS OHT OKT OMA OMB ONB ONL ORK OSJ OSW OTZ OVT OWI OWX OWY OYH | Anthem Blue Cross Blue Shield of Ohio |
| OAF OEA OEB OEM OHF OHG OSZ OTB OWJ OWS OWW OZD OZM | Anthem Blue Cross Blue Shield of Virginia |
| OCI OPD OPF OPJ OPK OPU OPV OPW OPX OPZ OZB | Anthem Blue Cross Blue Shield of Wisconsin |
| OBA OBQ OCA OCW OEH OES OFO OFP OIZ OKH OKW OOM OPG OQB OQP OQS ORL OTD OXD OXP OYB OZP | Anthem Bluecross of California |
| OKL OLM | Arkansas Blue Cross Blue Shield |
| OBU ODX OLN ONQ ONS OSB OTL | Blue Cross Blue Shield of Alabama |
| OBT ODM OLH OSE | Blue Cross Blue Shield of Arizona |
| OSM | Blue Cross Blue Shield of Illinois |
| OEG OLA OSY | Blue Cross Blue Shield of Kansas City |
| OCF OGS OGW OHI OPA | Blue Cross Blue Shield of Louisiana |
| OAB OAZ OBC OBN ODF ODT OMQ OMS ONG ONT OOC OPS | Blue Cross Blue Shield of Massachusetts |
| OAU OBE ODW ODY ODZ OEK OEQ OEY OFC OFJ OFQ OFU OFV OFW OFZ OGF OGJ OGK OGO OHC OHY OII OIJ OIK OIO OIQ OIT OIU OIV OIW OIX OIY OJE OJF OJI OJJ OJK OJL OJN OJO OJQ OJV OJX OJY OKF OKG OKI OKJ OKK OKN OKO OKQ OKV OKX OKY OKZ OLI OLQ OLV OLX OLY OLZ OMG OMP OMT OOD OOE OOF OOI OOJ OOK OON OOO OOQ OOU OOV OOW OOX OOZ OQD OQE OQF OQG OQH OQI OQJ OQK OQL OQM OQN OQO OQQ OQR OQT OQU OQV OQW ORF ORJ ORO ORQ ORV OTG OUD OUJ OUK OUL OUM OUN OUO OUQ OUU OUV OUX OUY OUZ OVD OVG OVI OVN OVO OVQ OVU OVV OVX OVY OVZ OWK OWO OWQ OWR OWU OXE OXG OXH OXI OXJ OXK OXL OXQ OXR OXT OXU OXV OXW OXX OXY OYF OYG OYI OYJ OYK OYN OYO OYQ OYR OYT OYU OYW OYX OYY OZE OZF OZI OZJ OZL OZN OZQ OZR OZT OZU OZV OZY OZZ | Blue Cross Blue Shield of Michigan |
| OBI OKA ONH ONY | Blue Cross Blue Shield of Minnesota |
| OAT OEI OSL OTC | Blue Cross Blue Shield of Nebraska |
| OOR | Blue Cross Blue Shield of North Carolina |
| OEW OTI OTN | Blue Cross Blue Shield of North Dakota |
| OKC | Blue Cross Blue Shield of Oklahoma |
| OFG OHE OHV OHX OHZ OJP OMR OOL OUB OUE | Blue Cross Blue Shield of Rhode Island |
| OEZ OHA ORI OUC | Blue Cross Blue Shield of South Carolina |
| ODJ ODL ODN OFN ORE ORG ORU OTH | Blue Cross Blue Shield of Tennessee |
| OHD | Blue Cross Blue Shield of Texas |
| OAD OCH ODI ODS OFF OFS OGT OIS OKS OLW OVL OWG OXA OXO OZS | Blue Cross Blue Shield of Western New York |
| OCT OID ORX OYD | Bluecross of Idaho |
| OPI | Bluecross of North Carolina |
| OAI OAL OBP OCD OCO OEJ OFT OFY OIP OLD OMH OMZ ONO OOA OOB OOG OOP OOS OOT ORY OSS OTM OTP OTX OWL OYL OYS OZG | Blueshield of California |
| OHM ORM | Blueshield of Northeastern New York |
| OFB ORT | Capital Bluecross of Pennsylvania |
| OAN OAQ OAR OBL OBM OCV OCX OCY ODA ODK ODO ODR OEF OEL OET OFL OFM OGX OJT OKB OKE OLS OMV ONU ONV OPT OSH OTJ OVR OWB OWD | Carefirst Blue Cross Blue Shield(Maryland/District of Columbia/Northern Virginia) |
| OAH OUH | Empire Blue Cross Blue Shield of New York |
| OBD OCK OEE OML OTA OWE | Florida Blue |
| OST | Highmark Blue Cross Blue Shield of Delaware |
| OAM OBB OBF OBO ODQ OEU OGU OHL OIB OIG OIL OIN OIR OPB OSQ | Highmark Blue Cross Blue Shield of Pennsylvania |
| OUW OVW | Highmark Blue Cross Blue Shield of West Virginia |
| OEV | Highmark Blueshield of Pennsylvania |
| ORN ORZ OUI OUR OUT OYC OZC | Horizon Blue Cross Blue Shield of New Jersey |
| OAK OBW OCR OCZ OIC OIM OKD OKM OKP OMD OOH OPY OQC ORD OSI OSO OSR OSV OTS OVC OYM | Independence Bluecross of Philadelphia and Southeastern Pennsylvania |
| OBJ OGM OLG OVH OXM | Premera Blue Cross Blue Shield of Alaska |
| OCN OER OJW ORS OTY OUA OUF OWC OXN | Regence Blue Cross Blue Shield(Oregon/Idaho/Utah/Washington) |
| OBR OCG OCM ODV OGC OGL OHK OHN OHU OJR OLB OLT OME OND OPP OPR ORB OSX OTK OTT OTU OUP OVM OWA OWF OWZ OYA | Wellmark Blue Cross Blue Shield of South Dakota/Iowa |