Which 7455 firmware to use?

IoT Modules
2

Hi Perry,
If you are using Verizon SIM, you can download firmware for Verizon carrier.
The latest firmware is here: https://source.sierrawireless.com/resources/airprime/minicard/74xx/airprime-em_mc74xx-approved-fw-packages/#sthash.Ygdnwsbc.dpbs

For EM/MC7455 you can load many packages to the devices, you can use AT!IMAGE? to list all firmware releases.
And AT!IMPREF="" command is used to select which carrier will be used.

Example: I loaded 2 carriers: GENERIC and SIERRA, and I used AT!IMPREF to switch these carriers as below:
at!impref?

 !IMPREF: 
  preferred fw version:    02.35.02.00
  preferred carrier name:  GENERIC
  preferred config name:   GENERIC_001.064_001
  preferred subpri index:  000
  current fw version:      02.35.02.00
  current carrier name:    GENERIC
  current config name:     GENERIC_001.064_001
  current subpri index:    000
 
 OK
 at!image?
 
 TYPE SLOT STATUS LRU FAILURES UNIQUE_ID   BUILD_ID
 FW   1    FOTA   129 0 0      ?_?         02.32.02.00_?
 FW   2    FOTA   128 0 0      001.028_002 02.16.06.00_GENERIC
 FW   3    GOOD   130 0 0      001.064_001 02.35.02.00_GENERIC
 Max FW images: 3
 Active FW image is at slot 3
 
 TYPE SLOT STATUS LRU FAILURES UNIQUE_ID   BUILD_ID
 PRI  FF   GOOD   0   0 0      001.064_001 02.35.02.00_GENERIC
 PRI  FF   GOOD   0   0 0      001.036_001 02.35.02.00_SIERRA
 Max PRI images: 50
 
 OK
 at!impref="SIERRA"
 
 OK
 at!reset
 
 OK
 at!impref?
 
 !IMPREF: 
  preferred fw version:    02.35.02.00
  preferred carrier name:  SIERRA
  preferred config name:   SIERRA_001.036_001
  preferred subpri index:  000
  current fw version:      02.35.02.00
  current carrier name:    SIERRA
  current config name:     SIERRA_001.036_001
  current subpri index:    000
 
 OK
 
 +CREG: 2
 
 +CGREG: 2
 
 +CEREG: 2
 at!impref?
 
 !IMPREF: 
  preferred fw version:    02.35.02.00
  preferred carrier name:  SIERRA
  preferred config name:   SIERRA_001.036_001
  preferred subpri index:  000
  current fw version:      02.35.02.00
  current carrier name:    SIERRA
  current config name:     SIERRA_001.036_001
  current subpri index:    000
 
 OK

Hope it can help.
Thanks,