iPhone Is it possible to unlock with iOS 6.1.3 on bb 05.13.04?

[karjm]

I managed to downgrade from baseband 06.15.00 to 05.13.04 and am currently on iOS 4.1. If I can preserve this baseband and upgrade to 6.1.3 could I unlock my phone while being on iOS 6? or can I at least upgrade to iOS 5 even though I don't have their blobs? Any help is much appreciated

I'm quite desperate right now for a working phone. Its a 3gs 16gb old bootrom. Just looking to to get out of iOS 4 and have an unlocked phone (which the imei is already unlocked)
Sorry for being a noob!

EDIT:
would this do the trick? any advice on this idea? http://www.evasi0n.bz/2013/04/update-iphone-to-ios-613-while.html

 

[dhlizard]

If it is old bootrom, you can use Sn0wbreeze to build a No_BB IPSW for 6.1.3.
It will give you an untethered jailbreak on 6.1.3 (because it is old bootrom)
Then install Ultrasn0w from Cydia to unlock 5.13.xx

 

[karjm]

If it is old bootrom, you can use Sn0wbreeze to build a No_BB IPSW for 6.1.3.
It will give you an untethered jailbreak on 6.1.3 (because it is old bootrom)
Then install Ultrasn0w from Cydia to unlock 5.13.xx

Success!! it works thank you so much
For anyone else with this problem, it helps to follow the link I have above. If you were also looking to unlock your phone and had problems, keep trying and rebooting your phone until Ultrasn0w downloads. Mess around with taking in or out the sim card and either turning on or off 3g. It might even help to download ultrasn0w fixer for 6.1. I've done all the above and got it to work.
I can confirm this works while being on 6.1.3 with frimware 05.13.04

 

[dhlizard]

Ultrasn0w fixer doesn't make any difference.

The correct procedure is once Ultrasn0w is loaded, instead of pushing the re-spring button, slide the phone to off, then back on.

One additional reboot might be needed.