Always back up your current running configuration ( copy running-config tftp ).
: The specific version (Maintenance Release 7 of the 15.8(3) train). c1900-universalk9-mz.spa.158-3.m7.bin download
: Make sure you have the appropriate licenses and are complying with Cisco's terms of service. Cisco software is copyrighted and its use is subject to licensing agreements. Always back up your current running configuration (