I've had a LineLink device for a few months now, and when it works, it seems to work well. However, like many others, I experience persistent failures in the LineLink service from time to time.
The failure mode is that inbound calls don't get delivered to the LineLink device, but instead are diverted to voicemail. Outbound calls fail with a "fast busy" or reorder tone. This is annoying because the device generates a dial tone when you go offhook.
This failure happens every so often. Once it gets into this mode, power cycling the LineLink device will resolve the issue. I also have a Vonage VoIP adapter in my home, connected to the same Ethernet switch and on the same network. It continues to work just fine. So probably not a problem with my router.
My guess is that there's a memory leak in the device. Or perhaps the registration with the T-Mobile network fails at the far end, but the device doesn't notice some stale registration. Not sure, there's no external visibility into the working of this box.
I used the be Chief Technology Officer at Vonage some years ago, so I've had some experience building residential VoIP products, and having them operate on random residential networks, behind all manner of crappy routers, cable modems and the like. I know it's possible to solve this problem, because I've personally done it. I would really like to have this service work reliably.
I'm about to set up some automation to power cycle the box every morning at 4:00AM. But that doesn't fix the problem, it only mostly avoids or recovers from it. From what little investigation I've done, this seems to have been going on with lots of end-users and for some time. I don't know why T-Mobile hasn't been able to fix this issue. From my personal experience when I ran a platform with more than 2 million VoIP CPE devices, we took these types of failures very seriously because lives are at risk since 911 calls probably don't work either.
Is someone from T-Mobile going to step up and commit to solving this issue? I opened a ticket and was told it was going to be escalated to engineering, but there was no clear response when I asked about what happens next, and how do I track this issue towards resolution? I'd be happy to work with someone from engineering to characterize the nature of problem and do some debugging.
If that's not going to happen, I guess I start calling and asking for bill credits every month, costing you guys money for the service, as well as another customer contact and those associated costs. And rebooting the thing every night, which is a totally crappy workaround to what should be solvable problem.