Security lock code - can I reset it?

I have a question, I have an older phone. My mom had it for about a year and a half before I got it, And I just got it in March. I don't know if she set the security code or what. But I accidentally locked a few phone entries. I would like to unlock them but my mom doesn't remember if she set the code or if it is just one that sprint had. But can you get around the security code, or reset it?

If you are prompted for a security code, first try the last four of mom's soc. sec. number, second try the last 4 digits of the original phone number for that phone. If that doesn't work, call 877.812.1223 and explain your situation to them.

It will also be helpful for them to know the model of your phone, look at the label under the battery for that.