What is the area code for Castro Valley, CA?

Castro Valley uses 2 area codes: 510 and 341. They overlay each other, so all of them cover the whole city and you dial 10 digits for local calls.

What time zone is Castro Valley in?

Castro Valley is in the Pacific time zone.

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Castro Valley, CA Area Codes

Castro Valley, California (population 65,389) uses area codes 510 and 341.

Area code510

Area code341

Time zonePacific

Local time now…

Castro Valley has no telephone exchange of its own in NANPA records; it is served by the Hayward exchange about 9.8 km away.

Castro Valley and nearby cities in area code 510

Carriers with Castro Valley numbers

130 prefixes are assigned to the Hayward exchange: 33% mobile, 25% VoIP and cable, 42% landline.

Carrier	Prefixes
AT&T (Pacific Bell)	36
Verizon Wireless	16
AT&T Mobility	16
Onvoy (Sinch)	14
Metropcs	10
T-Mobile	9
Bandwidth	5
Lumen (Level 3)	4

Area codes used in Castro Valley

Area code	Prefixes serving Castro Valley	Main carriers in this code
510	117	AT&T (Pacific Bell), AT&T Mobility, T-Mobile
341	13	Fractel, Onvoy (Sinch), AT&T Mobility

Castro Valley phone number prefixes

Numbers starting with these first six digits were originally assigned to the Hayward exchange.

510-200 Metropcs
510-209 Metropcs
510-244 Bandwidth
510-246 Verizon Wireless
510-247 AT&T (Pacific Bell)
510-258 AT&T (Pacific Bell)
510-259 AT&T (Pacific Bell)
510-264 AT&T (Pacific Bell)
510-265 AT&T (Pacific Bell)
510-266 AT&T (Pacific Bell)
510-274 Utility Telecom Group
510-276 AT&T (Pacific Bell)
510-278 AT&T (Pacific Bell)
510-293 AT&T (Pacific Bell)
510-294 Metropcs
510-300 Tpx Communications
510-303 AT&T Mobility
510-305 AT&T Mobility
510-310 Sequoia Wireless
510-314 T-Mobile
510-315 Lumen (Level 3)
510-317 AT&T (Pacific Bell)
510-329 AT&T Mobility
510-330 Onvoy (Sinch)
510-331 AT&T Mobility
510-340 Verizon Wireless
510-342 Tpx Communications
510-359 Verizon Wireless
510-361 Lumen (Level 3)
510-362 T-Mobile
510-363 Verizon Wireless
510-370 Peerless Network
510-372 Onvoy (Sinch)
510-397 Comcast (Xfinity)
510-398 Bandwidth
510-415 T-Mobile
510-427 Verizon Wireless
510-432 AT&T Mobility
510-460 Verizon Wireless
510-461 AT&T Mobility
510-470 Bandwidth
510-481 AT&T (Pacific Bell)
510-512 T-Mobile
510-514 Peerless Network
510-537 AT&T (Pacific Bell)
510-538 AT&T (Pacific Bell)
510-546 Onvoy (Sinch)
510-554 33 Wireless
510-566 Verizon Wireless
510-571 AT&T Mobility
510-576 Verizon Business (MCImetro)
510-581 AT&T (Pacific Bell)
510-582 AT&T (Pacific Bell)
510-583 AT&T (Pacific Bell)
510-584 Verizon Business (MCImetro)
510-586 Comcast (Xfinity)
510-589 AT&T Mobility
510-600 Onvoy (Sinch)
510-605 Verizon Wireless
510-606 Verizon Wireless
510-634 Verizon Wireless
510-670 AT&T (Pacific Bell)
510-674 Onvoy (Sinch)
510-677 Metropcs
510-688 T-Mobile
510-690 AT&T (Pacific Bell)
510-695 Verizon Wireless
510-706 Metropcs
510-723 AT&T (Pacific Bell)
510-727 AT&T (Pacific Bell)
510-728 AT&T (Pacific Bell)
510-731 Verizon Business (MCImetro)
510-732 AT&T (Pacific Bell)
510-733 AT&T (Pacific Bell)
510-736 T-Mobile
510-750 Metropcs
510-751 Onvoy (Sinch)
510-754 Metropcs
510-755 Metropcs
510-760 Metropcs
510-780 AT&T (Pacific Bell)
510-781 AT&T (Pacific Bell)
510-782 AT&T (Pacific Bell)
510-783 AT&T (Pacific Bell)
510-784 AT&T (Pacific Bell)
510-785 AT&T (Pacific Bell)
510-786 AT&T (Pacific Bell)
510-807 T-Mobile
510-819 Onvoy (Sinch)
510-825 Metropcs
510-826 AT&T Mobility
510-828 Verizon Wireless
510-856 Verizon Business (MCImetro)
510-861 AT&T Mobility
510-862 AT&T Mobility
510-876 At&T Enterprises
510-880 Onvoy (Sinch)
510-881 AT&T (Pacific Bell)
510-884 Utility Telecom Group
510-885 AT&T (Pacific Bell)
510-886 AT&T (Pacific Bell)
510-887 AT&T (Pacific Bell)
510-888 AT&T (Pacific Bell)
510-889 AT&T (Pacific Bell)
510-892 Onvoy (Sinch)
510-901 Bandwidth
510-909 Verizon Wireless
510-921 AT&T (Teleport)
510-925 Bandwidth
510-931 Lumen (Level 3)
510-935 AT&T Mobility
510-940 Tpx Communications
510-951 Verizon Wireless
510-954 Onvoy (Sinch)
510-962 Lumen (Level 3)
510-963 AT&T Mobility
510-999 Onvoy (Sinch)
341-208 AT&T Mobility
341-221 T-Mobile
341-232 Onvoy (Sinch)
341-240 T-Mobile
341-241 Onvoy (Sinch)
341-245 Onvoy (Sinch)
341-258 AT&T Mobility
341-260 Verizon Wireless
341-262 AT&T Mobility
341-271 Verizon Wireless
341-386 Fractel
341-777 Wide Voice
341-800 Fractel

Nearby cities in area code 510

Questions

What is the area code for Castro Valley, CA?: Castro Valley uses 2 area codes: 510 and 341. They overlay each other, so all of them cover the whole city and you dial 10 digits for local calls.
What time zone is Castro Valley in?: Castro Valley is in the Pacific time zone.