! Verify checksum (MD5 from Cisco’s download page) verify /md5 flash:C3900-universalk9-mz.spa.157-3.m8.bin
: The platform family. This image is exclusively compiled for the Cisco 3900 series, including models 3925, 3925E, 3945, and 3945E. It will not work on 1900, 2900, or any other series. C3900-universalk9-mz.spa.157-3.m8.bin
Transfer the image from your management workstation to the router's local flash memory using TFTP, FTP, or SCP: including models 3925