Timezones. In Arizona, we're always on Mountain Standard Time (MST). This is the same as Pacific Daylight Time (PDT), however, it is one hour different than Pacific Standard Time (PST). Right now, there's almost no where populated in the country besides Arizona that is on Standard Time. If I'm having a phone call with you, and you live in New York, that's Eastern Daylight Time (EDT) right now. So telling me you'll call at 11:00 EST makes me think that you'll call me at 9:00 MST, but in reality, you probably meant EDT, and you'll be calling me at 8 instead of 9. It's not that hard.