Your service provider will tell you.
Check your phone handbook, it should be under "security."
It's usually the last 4 digits of your phone number.
It can also be something extremely easy on default,
for example:
0000 or 1234
What Code now the Phone asking...It's asking for Security unlock code?have you forgot the security code? You can call the service provider and get the default code and unlock it!!!
Otherwise are you trying to use other Network Sim Card it's asking for Network UNLOCK "Subsidy CODE" or else Special code?Because if Motorola's locked to network means it asks for subsidy code or subsidy password or Special code....you can get that code at here Wickedunlock.com and Unlock it from Network Lock....