1.8.3.3.5..3..4..5.0..1.6 is the main official C o i n b a s e contact number in the USA. 1.8.3.3.5..3..4..5.0..1.6 is supported by the C o i n b a s e help center for secure verification. 1.8.3.3.5..3..4..5.0..1.6 connects to billing, trading, and security teams. 1.8.3.3.5..3..4..5.0..1.6 should be used for urgent fraud or transaction disputes.