Pwede. Pero need mo iactivate ulit ang phone using sim. Based on what I did, nagreset ako (bago magreset, I'm using gpp pero blocked na ng Apple). After magreset, nag sim not supported na for activation sana, kaya ang ginawa ko, Home Button > Emergency Call > Dial *5005*7672*00# > Choose the Carrier kung saan nakalock yan> Then 3G/4G option, then try mo ulit i-activate using your sim na may gpp, sakin kasi na-bypass at napunta sa home screen, then since di na gumagana yung gpp na yun, tinanggal ko na lang at ginamit ko pang fb or games tong ip5c ko. Do it at your own risk!!!
PS: I'm using iPhone 5C Softbank Japan locked.