AT&T/T-Mobile SIM unable to connect with 1002-CM04 plug-in modem

Problem

An Accelerated 63xx-series router is unable to establish a 4G LTE cellular connection when using an AT&T or T-Mobile SIM card and 1002-CM04 plug-in modem.

This issue only affects 63xx-series devices utilizing the 1002-CM04 plug-in modem variant.  The 1002-CM03 and 1002-CM06 modules do not experience this issue, and can connect reliably on LTE with AT&T/T-Mobile SIM cards.  To check if your 63xx-series router is using a 1002-CM04 modem, navigate to the Cellular Details tab for the device in Accelerated View, or to the System tab of the 63xx-series router's local web UI.  Look for the modem model.  The 1002-CM04 modem is listed with the following model name:

Telit MBIM_1BC7_0032

Background

The 1002-CM04 performs additional pre-registration steps when connecting to AT&T or T-Mobile's LTE network, which can interfere with the 63xx-series router's timing on establishing a cellular connection.  The result is intermittent or no connectivity on AT&T's LTE network.

Solution

Firmware versions 18.4.54.22 or higher resolves the connectivity issues on the 1002-CM04 module with AT&T/T-Mobile SIMs.  You can use the following instructions to upgrade a 63xx-seris router to the new 18.4.54.22 firmware:

https://kb.accelerated.com/m/67492/l/815080-updating-firmware#managing-the-device-locally

Manual Solution

Before implementing this manual solution, please ensure your 63xx-series router is running firmware version 17.8.128.64 or higher.

Users can lock the 63xx-series router to 3G only.  This allows the 63xx-series router to reliably establish a cellular connection with an AT&T/T-Mobile SIM and 1002-CM04 module, albeit on a possibly slower 3G connection.

To implement this manual solution, update the configuration profile of the Accelerated 63xx-series router with the following configuration changes:

  1. In Modem -> Access technology, set the value to 3G.