"E" is Eastern Time Zone, "C" is Central Time Zone, "M" is Mountain Time Zone, and "P" is Pacific Time Zone. Occasionally, an area code will fall in more than one time zone. In this case, the abbreviation is a combination of the previous abbreviations. Some area codes are shown with time zones referencing Universal Coordinated Time (UTC).
Additional technical status can be retrived from the North American Numbering Plan Administration on the 626 area code specific link here.
Area code 626 went live into service on June 14, 1997.  It was formed as a subdivision of the 818 area code.
Due to popularity, this area code is starting to run out of free telephone numbers for people to use which means that this area code is technically referred to as being "in jeoparady." Planning is underway and notices have been distributed regarding the area code subdivision.
PSDN PSDN, COVINA, ALHAMBRA, ARCADIA, MONROVIA, AZUSA, EL MONTE, LA PUENTE, SIERRAMADR, SNGBLCNN
Number of major cities served
Names of major cities served (ZIP code)
Pasadena (91101), Covina (91723), Alhambra (91801), Arcadia (91006), Monrovia (91016), Azusa (91702), Irwindale (91702), El Monte (91731), Anaheim (92805), Federal (92805), Weehawken (07087), Union City (07087), Bergenline (07087), Summit Avenue (07087), San Gabriel (91775), Baldwin Park (91706), Irwindale (91706), Sierra Madre (91024), City Of Industry (91748), La Puente (91748), Rowland Heights (91748), City Industry (91748), Rowland Hghts (91748), Rowland Hgts (91748), Rosemead (91770), Pasadena (91104), Pasadena (91107), City Of Industry (91746), La Puente (91746), City Industry (91746), Bassett (91746), City Of Industry (91744), La Puente (91744), City Industry (91744), Glendora (91740), South Pasadena (91030), S Pasadena (91030), (00000), Pasadena (91103), Los Angeles (90071), Arco (90071), Arco-plaza (90071), Temple City (91780), Van Nuys (91403), Sherman Oaks (91403), City Of Industry (91745), La Puente (91745), Hacienda Heights (91745), City Industry (91745), Hacienda Hts (91745), Covina (91724), Charter Oak (91724), West Covina (91792)
39 telephone companies servicing the 626 area code
List of telephone companies
O1 COMMUNICATIONS, INC. - CA, T-MOBILE USA, INC., CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA, XO CALIFORNIA, INC., U.S. TELEPACIFIC CORP. - CA, BROADWING COMMUNICATINS. LLC - CA, DIGITCOM SERVICES, INC., GLOBAL CROSSING LOCAL SERVICES, INC.-CA, PAETEC COMMUNICATIONS, INC. - CA, AT&T LOCAL, NEXTEL COMMUNICATIONS, INC., USA MOBILITY WIRELESS, INC., PAC - WEST TELECOMM, INC., COST PLUS COMMUNICATIONS, LLC - CA, TELEPORT COMMUNICATIONS GROUP - LOS ANGELES, NEW CINGULAR WIRELESS PCS, LLC, ALLEGIANCE TELECOM, INC. - CA, PACIFIC BELL, SPRINT SPECTRUM L.P., VERIZON CALIFORNIA INC.-CA (GTE), MPOWER COMMUNICATIONS CORP - CA, LEVEL 3 COMMUNICATIONS, LLC - CA, MCIMETRO ACCESS TRANSMISSION SERVICES LLC, COOK TELECOM, INC., SHELCOMM, ROYAL STREET COMMUNICATIONS, LLC, NETWORK SERVICES LLC, COMMPARTNERS, LLC - CA, THE TELEPHONE CONNECTION OF LOS ANGELES, INC., NORTH COUNTY COMMUNICATIONS CORP. - CA, POINTE COMMUNICATIONS CORP. - CA, TELCENTRIS COMMUNICATIONS, LLC - CA, PACIFIC BELL - CLEC, CHARTER FIBERLINK CA-CCO, LLC - CA, TW TELECOM OF CALIFORNIA LP - CA, MCI WORLDCOM COMMUNICATIONS, INC., CA, YMAX COMMUNICATIONS CORP. - CA, CROWN CELLULAR & PAGING, 360NETWORKS (USA) INC. - CA