The WiFi service from Google, in conjunction with Level 3 Communications, will be as much as 10 times faster than the current service, the company said.
The service will be rolled out in stages to 7,000 U.S. stores, starting with the busiest locations where WiFi usage is highest, and the transition should be completed in about 18 months, Starbucks said.
"This is obviously an important milestone in our relationship with Google," Starbucks Chief Digital Officer Adam Brotman told CNET. "We do hope this is one step amongst many that we can continue to build upon what's already a great partnership with Google."
An AT&T spokeswoman said her company had offered Starbucks a similar proposal of higher WiFi and network speeds.
"Starbucks continues to be an important customer for us and we continue to provide them with a variety of services over AT&T's advanced networks, including the nation's fastest, most reliable 4G LTE network," she said.
Starbucks stores are currently connected with a T1 line for 1.5-megabit speeds.
Level 3 and Google will upgrade the system in every location, although the actual speed boost will vary from store to store, Brotman said.
"When you start getting to really, really fast speeds, it's difficult to put it in the same way everywhere," he said. "Instead of finding one common denominator, we're saying, no, let's upgrade everything. It some case, it will be faster than 10-times, sometimes slower."
Starbucks' free WiFi, long popular with Internet users, is likely to be even more popular with faster connection speeds, he said.
"We're moving to much more of a streaming world across all media types," Brotman said. "This increased bandwidth will match what consumers are doing on the Web today, whether downloading or streaming or both."
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