Us cellular firmware em7455

Hello All,

Trying to get the US Cellular firmware to flash to a new em7455 module
Have messed with this for a full day. Have tried in both Windows 10 and Linux.
Always ends up within windows Skylight showing “Firmware mismatch” which iis the case
Trying to use a US Cellular sim,and with the GENERIC firmware am always getting 'no service"
Wanted to try the US CEllular firmware hoping the PRI information would make this sim card work



So yes you will need to use the US cellular firmware/carrier PRI file. Can you send the below commands to the unit.


I am guessing the last command will have a ‘fw mismatch’ in the response. Also assuming that you have managed to load the US cellular PRI file correctly and that the corresponding signaling firmware is on the unit if you send the below it could well sort it out.


Essentially you need to get the unit loaded with the US cellular carrier PRI and the signaling firmware and make sure it know it should be operating with it (which is what the IMPREF command does).



Hi Matt,

Thank You for the commands to try.
Regardless how many times i try to flash both windows and Linux Debian 11 the US-Cellular firmware will never load the PRI part for some reason.
Would like to try the The Sierra Wireless Mobile Broadband SDK with this Debian version to see if it will work correctly.
For example if i try to do a native ‘qmi-firmware-update ‘’’’- always fails with ‘could not open qmi device’
Even downloaded ,compiled from source a newer version of libqmi, hoping this may circumvent the problem,but did not.
I think the modem needs to be placed into qmi mode from mbim mode,but i’m not smart enough to enter the sequence of commands manually to make that happen.
Spent almost a full day trying to whip it,but it whipped me.
Wonder when Sierra Wireless support files/ Mobile Broadband Package for Linux SDK will become available.

EDIT: Failed to mention. I can get the module to straighten out to GENERIC firmware,but, I have to go back and forth from Linux and Windows 10 to get the module to have both firmware and pri matched to generic. It seem like one or other will never complete correctly.
I have done two of these modules previously,but they were the more common 310PY…code…on the module. Even those i had to monkey with some to get to latest generic firmware. It seems maybe the kernel versions,play up with qmi? Just a wild guess.
AM wanting to use a US CELLULAR sim with this module , hence wanting the US CELLUAR firmware just to explain.

Thanks again


Sorry for long message above
Forgot to mention,doing the

PRI Part Number: 9904748
Revision: 001.004
Customer: VenenoTablet

Carrier PRI: None

,even with what appears to be a good flash of latest generic firmware in both Windows 10 & Linux Debian 11.


No., this is not necessary. The Debian libqmi is built with support for MBIM and will automatically select the correct protocol by default. You can just run qmi-firmware-update without thinking about which mode the modem is in.

There is something else wrong. No idea what that is. But please try using the proxy if you haven’t already. I.e

qmi-firmware-update -p ...

Hi dl5162

Thank You very much.
The -p switch made the device flash as expected.
Am much closer now.
This is inside an Debian 11 machine and have the modemmanager gui installed. This gives a very good reference of what is going on with the modem, and stats etc.
After flashing with the US-CELLULAR firmware and successful…looked in ModemManager gui and could now see the US CELLULAR sim appearing. along with more stats.
Downside,after rebooting the PC this disappeared. Does the flashing procedure actually put the modem into mbim mode,or do i have to do this manually.
The last two modules i done EM7455 ,was only with generic firmware and with a lot of fiddling was able to make Daniel Wood ‘’ script do it’s thing. which does put the modem into mbim at end of script.
I never actually see the in the network connection manager the device /dev/wdc0,or whatever the modem shows up as there. to add to an connection for Mobile connection

Thanks again


Thank you for the suggestions.
Have been trying again to get this modem to work with US CELLULAR firmware
Here is what happens after flashing with the US-CELLULAR firmware
When i issues the above commands Matt suggested everything shows up correctly there.
BUT, when I go to the Connection Manager gui choose to make a Mobile broadband connection there is never a /dev/cdc-wdm0 showing as a device to make the connection.
If i do an at!rmareset=1 & at!image=0 then reflash with the GENERIC firmware there is in fact an /dev/cdc-wdm0 device to make a broadband connection.
Have done this numerous times now.



Hi Matt , again

Now out of the blue the modem did register.
Am thinking my signal is so weak may have been problem all along.
Only have the 'laptop antenna set" that came with the modem, Waiting on mhf4 to sma connectors along with 5 dbi antennas.

Current Time: 896 Temperature: 35
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B12 LTE bw: 5 MHz
LTE Rx chan: 5145 LTE Tx chan: 4294967295
EMM state: Registered Normal Service
RRC state: RRC Idle
IMS reg state: No Srv

–Debian 11 Bullseye
Have been trying a little further on the EM7455 with US CELLULAR firmware
Not sure why this happens but after doing an at!image=0 & at!rmareset=1 & reflash the module the US CELLULAR shows in ModemManager Gui, along with operator number and have a signal strength(very low).
Can reboot the pc many times this will show up again & again. As soon as i make a connection in the Connection manager and apply modem tries to connect and fails . After this the Operator & operator information never shows up in Modem Manager along with no signal. I can reproduce this again & again.

AT COMMANDS you sugggested

Manufacturer: Sierra Wireless, Incorporated
Model: EM7455B
Revision: SWI9X30C_02.32.11.00 r8042 CARMD-EV-FRMWR2 2019/05/15 21:52:20
MEID: 35399107096849
IMEI: 353991070968493
FSN: LF713576650110


PRI Part Number: 9904748
Revision: 001.004
Customer: VenenoTablet

Carrier PRI: 9999999_9907371_SWI9X30C_02.32.11.00_00_US-CELLULAR_000.039_003


FW 1 GOOD 1 0 0 ??
FW 2 EMPTY at!impref?

preferred fw version:
preferred carrier name: US-CELLULAR
preferred config name: US-CELLULAR_000.039_003
preferred subpri index: 000
current fw version:
current carrier name: US-CELLULAR




syslog trrying to activate modem from modem manager
Mar 6 10:17:55 dellinspiron NetworkManager[731]: [1646583475.1379] device (cdc-wdm0): Activation: starting connection ‘US CELLULAR’ (9019d335-85e9-4f36-b913-c4236245f138)
Mar 6 10:17:55 dellinspiron NetworkManager[731]: [1646583475.1383] audit: op=“connection-activate” uuid=“9019d335-85e9-4f36-b913-c4236245f138” name=“US CELLULAR” pid=7227 uid=1001 result=“success”
Mar 6 10:17:55 dellinspiron NetworkManager[731]: [1646583475.1386] device (cdc-wdm0): state change: disconnected → prepare (reason ‘none’, sys-iface-state: ‘managed’)
Mar 6 10:17:55 dellinspiron NetworkManager[731]: [1646583475.1396] device (cdc-wdm0): state change: prepare → need-auth (reason ‘none’, sys-iface-state: ‘managed’)
Mar 6 10:17:55 dellinspiron NetworkManager[731]: [1646583475.1428] device (cdc-wdm0): state change: need-auth → prepare (reason ‘none’, sys-iface-state: ‘managed’)
Mar 6 10:17:55 dellinspiron ModemManager[821]: [modem1] simple connect started…
Mar 6 10:17:55 dellinspiron ModemManager[821]: [modem1] simple connect state (4/8): wait to get fully enabled
Mar 6 10:17:55 dellinspiron ModemManager[821]: [modem1] simple connect state (5/8): register

Mar 6 10:18:56 dellinspiron ModemManager[821]: [modem1] 3GPP registration state changed (unknown → idle)
Mar 6 10:18:56 dellinspiron NetworkManager[731]: [1646583536.5810] modem-broadband[cdc-wdm0]: failed to connect modem: Network timeout
Mar 6 10:18:56 dellinspiron NetworkManager[731]: [1646583536.5811] device (cdc-wdm0): state change: prepare → failed (reason ‘gsm-registration-timeout’, sys-iface-state: ‘managed’)
Mar 6 10:18:56 dellinspiron NetworkManager[731]: [1646583536.5831] device (cdc-wdm0): Activation: failed for connection ‘US CELLULAR’
Mar 6 10:18:56 dellinspiron NetworkManager[731]: [1646583536.5837] device (cdc-wdm0): state change: failed → disconnected (reason ‘none’, sys-iface-state: ‘managed’)

Will attach a screen shot of Modem manager. This is after making the connection in Network manager
Before this US CELLUAR and number and signal is showing,but very low signal. Waiting in 4dbi antennas. Only have the bundled wire antennas for laptop
This USC sim card does work in a USC hotspot device

Thank You