"During the following process the memory of your iPhone will be reorganized. This will have a positive effect on the quality of the GPS reception. The internal memory will be deleted completely during this reorganization. Therefore it is necessary to make a backup of the software (as described in step 1). 1. Please connect your iPhone to iTunes and synchronize it. Afterwards please rightclick on the iPhone icon (in the left menu bar of iTunes) and choose "backup". iTunes will now create an complete backup of your iPhone content and settings. 2. Disconnect your iPhone from the computer and connect it to the power supply. 3. On your iPhone choose "Settings" -> "General" -> "Reset". 4. Choose "Erase all Content and Settings" and confirm the deletion. 5. The following erasing procedure can take up to two hours and more, depending on the model and storage capacity of your iPhone . 6. After the procedure has finished, please connect the iPhone to your computer again. 7. Now restore your content and settings to your iPhone using the previously created backup. In addition, a limited GPS reception can have the following reasons: Poor positioning of the iPhone in the car. Like every portable navigation device, the iPhone should always have a "free view" to the sky. Metallized windshield. Usage of design covers or protective covers. While using our NAVIGON software, please avoid using such covers as they can severely impair the reception of a GPS signal. This entry was last updated on: Wednesday, March 30, 2011 6:59 PM" Will going through this process mess up my Jailbreak?? In other words, can you do this on a Jailbroke phone?