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Similar issues could be related to firewalls/routers not passing IPv6 traffic. Clear-Com has used a Cradlepoint router to help troubleshoot this type of issues.
Recently (2023) it has been discovered that instances when customers choose to use a different port other than 6001, T-Mobile has blocked the port such as port 6002. One work around solution has been to use a VPN on the mobile device.
For additional assistance, please contact Clear-Com Technical Support
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