"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 415 area code specific link here.
Area code 415 went live into service on January 01, 1947.  This area code was split to create the 805 area code(s).  It has had the 408, 510, 628, 650 area code(s) overlaid on it.
This original "parent" area code went live on January 01, 1947 and due to growth it has been "overlaid" by the 628 area code to provide more telephone numbers in the area. This means this original "parent" 415 area code has seen quite a bit of growth and as a result has been subdivided into 2 area codes over the years. 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." Although planning efforts have been put on hold, a notice has been distributed regarding the area code subdivision. 2
San Francisco (94108), San Francisco (94115), San Francisco (94110), Novato (94947), Anaheim (92805), Federal (92805), San Francisco (94118), San Francisco (94143), San Geronimo (94963), Novato (94949), Bel Marin Keyes (94949), Ignacio (94949), Inverness (94937), San Francisco (94112), San Francisco (94103), San Francisco (94122), San Rafael (94901), San Anselmo (94901), Sausalito (94965), Muir Beach (94965), Marin City (94965), San Bruno (94066), Mill Valley (94941), Muir Woods (94941), Strawberry Point (94941), Tamalpais Valley (94941), Nicasio (94946), Larkspur (94939), San Francisco (94124), Belvedere Tiburon (94920), Bel Tiburon (94920), Belvedere (94920), Tiburon (94920), Point Reyes Station (94956), Pt Reyes Sta (94956), Pt Reyes Station (94956), San Rafael (94903), Marinwood (94903), Santa Venetia (94903), Terra Linda (94903), Stinson Beach (94970)
45 telephone companies servicing the 415 area code
List of telephone companies
O1 COMMUNICATIONS, INC. - CA, NEXTEL COMMUNICATIONS, INC., T-MOBILE USA, INC., AMERICAN MESSAGING (AM), INC., PACIFIC BELL, NEW CINGULAR WIRELESS PCS, LLC, USA MOBILITY WIRELESS, INC., VERIZON CALIFORNIA INC.-CA (GTE), CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA, U.S. TELEPACIFIC CORP. - CA, TELEPORT COMMUNICATIONS GROUP - SAN FRANCISCO, PAC - WEST TELECOMM, INC., AT&T LOCAL, SPRINT SPECTRUM L.P., GLOBAL CROSSING LOCAL SERVICES, INC.-CA, XO CALIFORNIA, INC., MCIMETRO ACCESS TRANSMISSION SERVICES LLC, INFOTELECOM, LLC - CA, LEVEL 3 COMMUNICATIONS, LLC - CA, BROADWING COMMUNICATINS. LLC - CA, METRO PCS, INC., YMAX COMMUNICATIONS CORP. - CA, MPOWER COMMUNICATIONS CORP - CA, CF COMMUNICATIONS, LLC DBA TELEKENEX - CA, PACIFIC CENTREX SERVICES, INC. - CA, COST PLUS COMMUNICATIONS, LLC - CA, CREATIVE INTERCONNECT COMMUNICATIONS, LLC - CA, ALLEGIANCE TELECOM, INC. - CA, TW TELECOM OF CALIFORNIA LP - CA, COOK TELECOM, INC., ASTOUND BROADBAND, LLC - CA, MCI WORLDCOM COMMUNICATIONS, INC., CA, SBC INTERNET SERVICES, INC., NETWORK SERVICES LLC, NORTH COUNTY COMMUNICATIONS CORP. - CA, UTILITY TELEPHONE, INC. - CA, DIGITCOM SERVICES, INC., CBEYOND COMMUNICATIONS, LLC - CA, COMMPARTNERS, LLC - CA, NEUTRAL TANDEM-CALIFORNIA, LLC - CA, PG TELECOM OF CALIFORNIA INC. - CA, COMCAST PHONE OF CALIFORNIA, LLC - CA, SOUTHWEST PAGING, PACIFIC BELL - CLEC, THE TELEPHONE CONNECTION OF LOS ANGELES, INC.