Hmm...what am I doing wrong?
I just tried what you advised, Neo, and it didn't exactly work (although it almost did, which is odd)...here is what happened:
-1.1.3 ZiPhone JB, AT&T (not unlocked)
-Windows machine (Vista x64 or XP x86, I still have my dual boot from before the iPhone worked in Vista x64); since iPhoneBrowser was giving me fits in Vista x64, these procedures were applied in the XP environment.
-Using iPhoneBrowser, I went into /Applications/MobilePhone.app/ and grabbed a copy of DefaultDialer.png (for backup). I renamed this file (I called it OLDDefaultDialer.png) and moved my new file (that I edited in Photoshop), called DefaultDialer.png.
-In iPhoneBrowser, it shows the new file just fine when I look at DefaultDialer.png preview.
-I restart the phone; I open up the Phone application and hit the dialer; my custom dialer image pops, and then (literally 1/2 a second later), it disappears and loads the 'original'. The dialer works fine fwiw. Every time I open the dialer app, it will have the default loaded from then on. If I repeat the above-mentioned process, it does the same thing: it alters the image for the first half second after reboot, then it reverts to the original.
-To combat the problem, I deleted the original file (since I have it backed up on my machine), hoping that it would then be unable to restore it on top of my edited copy. To my surprise, the same behavior as mentioned above continues to occur (suggests to me that the original DefaultDialer.png must be elsewhere on the phone besides MobilePhone.app if it's able to find it still after I have deleted the original from that folder).
Edit: -I tried one additional step (suggested on a different forum), which was to make the perms on the new file match the old. Indeed, the old file was rw-rw-r--. So I set the new file to that. No change. That same forum suggested using chmod 0777 on the MobilePhone.app folder itself, but I thought I should get some advice before I go messing around (especially since there's no ZiPhone for 1.1.4 in case I screw up).
I would appreciate any suggestions tremendously; this was one of the customizations I was most excited about when I decided to try out jailbreaking. I have done some searching (both on this site and on others) and I'm not finding what it is I'm missing or might have done wrong. I did try using the Customize app dialer keypad setting, but that affects the dialer that appears when you are in a call (and choose show keypad), not the 'main dialer' part of the phone app.