When planning a call between New York and Los Angeles, you need to consider that the cities are in different time zones. New York is 3 hours ahead of Los Angeles. If it's 3:00 p.m. in New York, it's 12:00 p.m. in Los Angeles. If you are in New York, the most convenient time to accommodate all parties is between 12:00 pm and 6:00 pm for a conference call or meeting. In Los Angeles, this will be a usual working time, between 9:00 am and 3:00 pm.

Source: 24 Time Zones