Can an unlocked iphone upgrade to ios 7 beta?

I have been trying to update my friends phone to ios seven beta but i keep running to the unconpatible firmware i have tried downloading the firmware for both model
Cdma and gsm but no dice i also tried downloading it from multiple sites but no luck can you tell me what i'm doing wrong what i should do and or if an unlocked phone can be upgraded btw i tried both holding shift an clicking update and holding shift and clicking restore ps its my friends phone so i don't know if its been factory unlocked or hack unlocked

No, during the update of the firmware, it will restore any changes that shouldn't be, and then you have to get it cracked after they figure out how to do it on the new firmware.

Any compatible phone can upgrade, the fact that your phone is carrier unlocked doesn't change a thing, you need to download a valid.ipsw file then sign it

Have you registered your device's UDID yet? You won't be able to activate iOS 7 unless you do that. I used http://www.instantudid.com/ and they were great. It's $5 and they do it instantly.