AT&T is resuming online sales of iPhones to New Yorkers after suspending them over the weekend for unclear reasons.

A spokesman said only that the phone company periodically "modifies" its distribution channels.

On AT&T Inc.'s Web site, buyers who supply New York City ZIP codes were told on Monday morning to "Please shop for another phone."

AT&T has acknowledged that its data network is overburdened with iPhone users in New York and San Francisco, sparking online speculation that the sales suspension is a means of managing traffic.

However, because the phones are still available in New York retail stores and from Apple Inc.'s Web site, the ban could instead be a way to curb fraudsters who buy phones and sell them on, reneging on the service contracts.