LineLink drops calls with 3 beeps

Just set up my LineLink a few days ago.

It regularly drops both incoming and outgoing calls after a variable amount of time, always preceded by 3 beeps.

I've checked my connection speed and quality and it meets the T-Mobile standards.

Tech Support doesn't know what's wrong.

Anyone else had this problem?  What was the solution?


Best answer by tmo_amanda 2 May 2017, 17:23

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Userlevel 4

Hmmm. Ya stumped us, @jimbabwe2! Let me see if we can get this figured out.

-What type of internet connection are you using (Cable Internet, DSL, Public WiFi, or FiOS)?

-Do you have a computer or laptop connected to the internet at home? If so, please go to and let me know the ping, upload and download speeds along with the QoS percentage.

Once I have that info, we can take a closer look if that's the reason for the random dropped calls or if it's something else.


And T-Mobile told me no one else but me was running into this issue. It has been going on for weeks. I've called and filed numerous tickets with customer service and "engineering" keeps coming back with NTF (No trouble found). I had to pay an RMA for a problem that wasn't mine. I knew that from the get go. So got a new unit, and bingo; same issue.  This is insane. I don't think they have a clue on how to debug this thing. I've been hitting my head against the wall with these guys. Great customer support though, but terrible engineering.  I am a former telecom engineer for a major Telco equipment manufacturer working in R&D research lab, and as such one of the very early adopters of SIP, H248/MEGACO protocols 15 years ago, so needless to say that I kind of know my way around these things.

So, I finally decided to cut the chase. I took the bull by the horns and inserted a Raspberry Pi as GW with wireshark analyzer on it to trace the problem at the protocol level. Interesting, but without more access to the software that seems to be patent protected, there isn't much I can do to nail down what is exactly going on and offer a fix.

That said, I now have some traces that capture the dropped call and ready to transfer to engineering and troubleshoot the issue. Happy to transfer the document to anyone at T-Mobile interested.  


I made the technical support people aware of your post.  Hopefully, someone has contacted you so you may provide the technical data you've acquired.

I've told tech support that I don't wish to pursue replacement or troubleshooting of the device on my end, since my ISP has checked my connection and assured me of its quality.  Based on your experience, it seems to be either a device-wide issue or an issue with the software on T-Mobile's servers.

Thank you for making them aware of it. 

I agree with your approach. It's not a device issue. I had to go through this process myself and at my own expenses, to prove this point.

Just so you know, as of today, I'm still supposed to receive a follow up call from someone of customer care @TMO this week and if that happen, I will offer the traces I captured with the dropped-calls in it. It's impossible for me to go any further and troubleshoot the issue unless I get the private keys. Which they won't share with me for obvious reaons. 

To me, it's just a bug somewhere between the SW running on the Linelink device and their media gateway server at TMO (with an additional gateway platform in between that is where the bug resides IMHO), and I'd be more than happy to assist them troubleshooting this issue with their R&D.

I'm not sure this "community platform" is very useful others than realizing we have similar issues among each others but I'm hoping that the more we are to complain about this issue, the higher it will go into their priority list.

Userlevel 4

Hey, @jimbabwe2!

I'm glad @pchevallier has chimed in as we now know you're not alone in this. @pchevallier you bring up a good point that our Support Community can only do so much troubleshooting as Community Managers do not have access to file tickets or any account access for that matter. I'm going to be completely honest with the both of you. This is very much over my head but that doesn't mean that I won't work to find answers.

@pchevallier, did you receive a callback yet? If so, what was the outcome?

Do either of you have tickets filed and have the ticket number available?

Hi Amanda,

Yes, I have a ticket filed but I don't know the number.  You can check with the team in Colorado Springs.


Hey Amanda, Thanks for reaching out,

Yes, Kevin (TMO Customer Support) has been following up with me and told me once again that engineering was rejecting all responsibility for this issue. They (R&D) are pointing the finger at our ISP.

As mentioned elsewhere on this community support, I told him that I have moved to a different ISP, including using TMO LTE data network, and the exact same problem occurred.

Interestingly, the problem doesn't seem to happen when calling a number owned by TMO, which might explain why R&D hasn't seen this issue. They are probably testing against their own telco network.

Kevin has since escalated this issue internally one more time in hope they will reach out to me for help. Nothing as of today (Friday). Kevin will follow up with me one more time next week. Kudo to this customer support employee who is going above and beyond all expectations.  I would have given up and gone to a different VoIP solution by now without his support.

Userlevel 4

Thank you both for responding, @jimbabwe2 and @pchevallier. Any updates on the tickets that were filed for you?

Nope, non, nein, niet, zero, zilch, zip, nada.

I don't make any long distance calls from this line any longer anyway. Incoming calls only. Good thing I have a 50% discount rate on this service, that matches what I'm using it for in the end 😊

I've been contacted by one of the support personnel in Colorado Springs who has been told by the engineers to replace my brand-new LineLink.  I'm not going to do it.  Based on the other information in this discussion, I believe the problem to be NOT with my device.

Userlevel 4

Ahhh! I was hoping for better news from the both of you. 😥

@jimbabwe2, I'd have to agree with you. Again, I'm far from understanding devices on the technical level that you and @pchevallier have, but from everything I've read in this thread, the device doesn't seem to be the cause. I'm going to pass this thread along to an individual that's involved with LineLink to see if we can get more eyes on the issue. That being said, there may be a point where I need to send you a PM to get a few details from each of you. If/when that becomes the case, I'll be sure to reply to the thread first so you receive a notification.

Thank you both for being so active on this thread!

We are also experiencing the same issue. We know the connection is good (ISP confirmed). Let us know if there is any way to resolve. Thanks.

@tmo_amanda, as you can see, we have one new user (@mwiner) who is experiencing the exact same issue, but I'm sure there are many more who are not taking the time to file any complaints.

I moved to my summer home with a different ISP and I still experience the exact same issue. I even collected new set of logs for TMO R&D to look at when they deem this is becoming urgent enough.

Userlevel 3

Hey all - I just wanted to touch base with you and let you know Amanda is working on this but waiting to hear back regarding any updates that we can provide.  Thank you so much for your patience, she'll report back as soon as she has news!

- Marissa

Hello Marissa - Thank you for the update.

Frankly I'm not sure about the value of your comment other than telling us "don't go away just yet", but this is dragging on for much too long now and I am about to post an article on Linkedin about this issue in the telecom equipment provider group who, I'm sure, will be interested to hear about this. I believe some members of that group are part of TMO. That's going to be interesting to get their attention that way.

Once again, I have a log file available in Wireshark format I'd be happy to provide to the engineering team so they can see by themselves the LineLink unit is NOT the cause of the problem, nor the ISP or any other customer related issue and dig into the code of the server side.

Userlevel 3

@pchevallier‌ - I understand your hesitance.   I just wanted to check in on the thread to keep it alive and advise that we're still working on it.  Amanda is trying to get information directly from the LineLink team - we can also advise them of the available logs you've collected to see if that would be of further assistance! 

- Marissa

Last Update

I received a call from tech support yesterday to inform me that engineering was not willing to follow up with me directly.

They are not interested in my findings and keep claiming this is an ISP only issue (typical finger pointing technique) and so despite that:

1 - I changed my ISP several times (including using T-Mobile LTE network to connect to the Internet !!)

2 - I confirmed the disconnect would occur on outbound calls only (which pretty much disqualify the problem from being the ISP or why would the inbound call not get disconnected?)

Unbelievable and very disappointing customer service !

Time to switch.

Our calls are dropped on incoming lines as well. Calls only began dropping after the use of LineLink so it’s very doubtful it could be an ISP issue.

I too am experiencing dropped calls, both incoming and outgoing. I spoke with tmobile engineering and filed a trouble ticket with them a few weeks ago. I also mentioned my problem with a ridiculously short dialing timeout. A pause of three seconds between digits results in being cut off. Haven't heard anything from them about either of these issues.

Now the middle (phone) status light on the LineLink is occasionally showing orange.  It fixes itself after some time.  I do not know the amount of time which elapses for the fix, as I don't know when the light turned orange nor do I know when it goes back to blue.

When I pick up the phone when the light is orange, I get a message telling me my phone has a problem.

I think this system has a problem, and it's not with my ISP.

One could imagine that T-Mobile  has a way to trace your event logs on your device and figure out why that is but I haven't seen proof they have deployed such capabilities in their XMPP device management layer (what they use to push remote firmware upgrade for instance).

By experience monitoring the LED activities against the network traffic on my network analyzer, I can tell you that the second LED goes from black to orange when the connectivity is ready to be established with their VoIP server (the green LED blinks when it waits for its DHCP IP address from your local router), and it turns steady blue when the unit is finally registered into their cellular network. In the TELCO industry, we call that equipment the Home Location Register (HLR). This is the final stage before you can place or receive a call. (it's similar to the DNS of the cellular infrastructure network). The voice you hear simply comes from a pre-recorded message located in your device that just reports a general connectivity issue but it doesn't go into any more details, hence why I would think T-Mobile does have some backdoor mechanism to troubleshoot these types of issues. Wishful thinking though 😥

To all the great people from customer-support at T-Mobile who have supported me all this time, as mentioned here's the link to my article I just published on that matter (click on the image and you'll be taken to the full article)

Thanks for posting that, Philippe.  Hopefully it will get someone's attention.

I wrote to the V.P. Customer Service (with a letter, an envelope and a stamp) and I certainly did get attention, such as a call from the office of the president of T-Mobile, John Legere.  No, not him personally, but someone from his office.  It was about another issue, which was quickly rectified to my satisfaction.

I've left my LineLink technical troubles to T-Mobile's support team in Colorado Springs.  So far, their hands are just as tied as yours:  engineers report no fault found.

Funny thing is that my wi-fi calls from my Samsung are also dropping.  Wonder if it's the same AWS VoIP server...

I suggest you write a letter, put it in an envelope, and mail it to Bellevue, Washington, to the V.P. in charge of engineering.


"Funny thing is that my wi-fi calls from my Samsung are also dropping.  Wonder if it's the same AWS VoIP server..."

I imagine that is the case. There shouldn't be any difference between the LineLink® and WiFi Calling feature on the cell phone but the connection to the Internet.

Thank Jim you for sharing that piece of information.

As for the LineLink® itself, I am convinced this is the right way to go. I have worked on VoIP for 15 years, and the idea to bring the SIM card to the unit was brillant. It insures security (encryption) and manageability exactly as we have on our cell phone.

As we know, any internet based product (also known as Internet of Things) are very vulnerable and the use of the SIM card makes this device pretty much unbreakable.

This is a technology we have been working on for 20+ years on GSM in Europe, and this is finally coming to our home.

The next step this product could take is to add a video port and compete head to head against Facebook Messenger, MSFT Skype, Google  Hangout and Apple FaceTime to name the most popular ones.  those companies are currently working on a new TELCO infrastructure that is going to revolutionize this industry and T-Mobile  might die or just relinquished as a cell-network infrastructure provider if they let themselves get side-blinded by those giants.

Just had a 25 minute incoming call drop with three beeps... the LineLink is completely undependable