Internet provider Sky Broadband has promised customers of their service, specifically those connecting via the latest ‘Sky Max Hub‘ router, that a fix is on the way for a long-running bug that appears to be preventing users from being able to use Wi-Fi Calling when on their home network.
Most people probably already know this, but Wi-Fi Calling (aka – VoWiFi) enables consumers with a supporting Smartphone and mobile operator to harness their home broadband connection or other WiFi service to make mobile voice calls, instead of using your mobile (2G, 4G or 5G) network. The feature is extremely useful, particularly when away from a good mobile signal, but support can be patchy between different networks and devices.
However, some customers with Sky’s Max Hub router have been complaining (Sky’s Forum), at least since around early December 2024 (or possibly earlier), that they’ve been unable to get Wi-Fi Calling working at home. So far as we can tell from the feedback, this issue appears as if it could be down to Sky Broadband’s relatively recent implementation of MAP-T based IP address sharing (details).
Sky were one of the first UK ISPs to adopt MAP-T last year, which is generally an improvement compared with the much-maligned Carrier Grade Network Address Translation (CGNAT), but it’s not perfect and can sometimes conflict with certain online services.
In this case, MAP-T also appears as if it may have caused problems for some customers with Wi-Fi Calling, which is supported by the fact that those who have made a request for the feature to be disabled were able to get the service working again. Unfortunately, this fix doesn’t seem to last, and some users have reported that it returned a few weeks later. Sky are aware and working on a fix.
Sky’s Community Manager, Kev, said:
Thank you for bringing this problem to our attention.
I’d also like to thank you for your perseverance and patience whilst we work through this technical issue.
Our support teams are working on a solution, and we will be updating customers connections automatically.
So that everyone has access to the most recent update, I’ll be marking this post as the answer. It doesn’t mean that the issue is resolved, it confirms that we’re working on the solution.
Sky’s statement was posted nearly two weeks ago and customers have yet to see a fix being applied, but hopefully they won’t have to wait too much longer. In the meantime, those who want to try working around the issue could try using Sky’s VPN request form, which relates to an MTU tweak that when applied may be able to resolve the issue, at least temporarily. More advanced users can also try applying this themselves (details here).