HL7800 Downgrade instructions + NO CARRIER issue

Hi all,

This topic may be better described as a combination of something problematic I’m seeing, and a question regarding operating the HL7800.

First for the problem; I have built an application built on a Bluetooth controller which communicates with the HL7800 and have it working fine in most instances. One unit however, while running the same application, will consistently get ‘NO CARRIER’ while in the process of closing a TCP connection which causes some issues. The only difference with this unit that I have observed is that the firmware on the modem is 4.6.8 compared to 4.4.14 on my other devices.

In order to confirm whether this is the root cause, I wanted to rollback the firmware to the same version, however when I performed the same process as I normally do (XModem upgrade), the firmware version stayed the same. My question is now how can I revert the firmware to do confirm whether a change in the modem version is indeed causing the issue?

Any help for both concerns is greatly appreciated,


EDIT: For whoever tackles this later, I’ve duplicated this on a second unit by upgrading it from 4.4.14 to 4.6.8 and see this issue happen again. Would there be changes in how it handles closing connections / sockets / something where NO CARRIER occurs? This creates an error code 922 following it which is tied to an invalid state of the session.

Hi @Antoine,

1, If you cannot use XModem to upgrade successfully, you can use Windows One-Click to upgrade (at this link: https://source.sierrawireless.com/resources/airprime/software/hl7800-firmware/hl78xx-firmware-4,-d-,4,-d-,14,-d-,0/#sthash.eW9TO97N.dpbs).
2, Can you provide me the log when this issue happened?
3, Do you have another TCP Server? You can try with other TCP Server and check again.


Hi Jerdung,

Sounds good, the direct method of changing the firmware worked great!

As for the logs; would I be able to send them to you directly? I’ve removed the sensitive aspects of it but I would like to preserve some of the log data.

As for a different TCP server, we don’t have one currently where we could operate in a similar manner.

Since we are alright with 4.4.14, we are alright moving forward but if you need anything for your own side just let me know and I can try to get you what I can.



Hi @Antoine,

I am glad to hear that your modules are working well with FW 4.4.14.
You can contact me if you have any issue.


Hi again!

I wanted to come back to this issue as the need to resolve it has grown. As I’ve recently learned that all modules that we will be receiving will have version instead of the previously installed, and that we will need a firmware update to allow for IMSI switching in the future, I tried to tackle this a second time.

What I’m seeing still seems to show signs of problems with the modem returning +NO CARRIER during an attempt to close a TCP connection. I was wondering what could I supply to potentially help learn more on Sierra’s side what’s going on?
I attached two pictures of the disconnection process below, the first being a good disconnection from version, and the second being the issue I’m facing in If there is more information I can provide which would help lead me to what’s changed just let me know as the issue happens consistently.


Should I open a new topic since this one has been here for a month or so already?