We purchased ZTE Warp Connect hotspots from Mobile Beacon about a year ago. They use Sprint towers. We liked them a lot, but this spring received an email saying there have been issues with the batteries swelling, and in some instances catching on fire. We are not circulating them at this time. Mobile Beacon told me they would replace them, but have not been able to say whether the problem has been fixed. I'm wondering if we should try a different company. I would appreciate hearing the responses you get to this question.