AT&T’s deal to exclusively carry the iPhone in the US is set to expire next year, according to a report in the Wall Street Journal, with the telecom company working hard to extend the agreement to 2011.

Neither Apple nor AT&T commented, with an Apple spokesman claiming, “We have a great relationship with AT&T,” according to the report.

Apple’s iPhone is a big money maker for AT&T, bringing in over 1.7 million new customers with the iPhone 3G last year. Though, AT&T has not been a favorite among iPhone fans who complained about long-term contracts, high termination fees, and poor network performance in major urban areas.

The Business Insider points out that Apple may want to stick with AT&T for the time being and save on any production costs in trying to fit the iPhone to other carrier’s 3G networks. Once 4G is realized based on the universal LTE technology, Apple could then shop the iPhone to the best carrier.