SIM7670G connect problems, but its T-Mobile certified

[Sid1]

We have been testing a few different core boards like this having A7670G, SIM7670G, and SIM7600NA-H SIMCOM modules, using 4G LTE, for a frustrating couple of months. The ASR baseband chipsets used in the SIMCOM A-Series (like A7670G) were found not certified for use in the USA, causing registration loss. The SIM-series however has Qualcomm bb chipsets and are mostly listed in T-Mobile’s list.

My big question is, Why would a SIM7670G not maintain network connection? They disconnect/de-register (apparently) like the A7670G tested. The SIM7600NA modules work perfectly. Its on the TMO cert list.

There is no SimCom tech support that responds to emails. The Simcom sales rep, John Foucher, has not responded to my emails about this. There is no SimCom forum.

Do we have a bad SIM7670G module? Is anyone else using this module successfully?

[Steve_Fellman]

Hello,
Welcome to the DigiKey TechForum. I’m wasn’t successful in finding information that may assist you. I sent a request for information and will post what I receive. In the meantime someone with more experience with this may jump in and offer a solution.

[APDahlen]

Hello @Sid1,

This is a difficult problem to troubleshoot.

As I understand your situation, there are several potential problems. IMO, they are listed here in order of decreasing likelihood:

• the board/module is defective, or your software is at fault
• your local cell service is not operating as expected
• the SIMCOM module itself is defective

While I don’t have SIMCOM specific advice I can offer these general suggestions:

• look for shielding or a ground plane in the vicinity of the antenna
• move physically closer to the cell tower
• use a clean software built with minimal functionality (preferably the demo program provided by the OEM)
• purchase a replacement module to elevate the possibility of device / module failure

Sorry, I could not provide a better answer.

Best wishes,

APDahlen

[David_1528]

Hi Sid1,

First of all, I assume you are referring to the SIM7070G rather than the SIM7670G, which I could not find to be a valid part number.

Looking at SIMCom’s product web page for the SIM7070G here, the SIM7070G does appear to be compatible with T-Mobile, so that’s good.

If you haven’t yet done so, I would recommend you download and read through the relevant documentation listed at the bottom of the product web page I linked to above. It requires you to first register before downloading. There may well be relevant information there to help with your issues.

Image of documents at bottom of their product page:

[Sid1]

SIM7670G
See SIM7670G listed by T-Mobile.

I have the boards on my desk…
I practically have the Docs memorized.
This isn’t landing a first-stage of a rocket it should not be disconnecting. Right?