Go into dialer/phone, dial *#*#4636#*#*. This sometimes does not work, so just redial it if anything. Afterwards, go into "Phone Information". On the bottom right corner if the screen, there will be the menu icon (3 squares lined up). Click on it, then choose "Select Radio Band".
3 Options will appear:
USA Band - Does not seem to work
Cellular - This will force roam onto Verizon, US Cellular, etc (all companies that utilize the 850 MHz band)
PCS - Should be Sprint Native signal for the most part. (1900 MHz, so pretty much Sprint)
Note: As of now, this should work as a decent workaround to force Roaming, however, Sprint will be deploying 1x (Voice) over the SMR spectrum, or simply put, the 800 MHz frequency. I am not sure if the phone will connect to Sprint's 800MHz frequency when available, or it if it will connect to Verizon's 850 MHz. This will not only come into play in Network Vision areas, but will eventually impact all of Sprint's network, as all towers will receive Network Vision.
Thank you, Thank you, Thank you!