no tmobile carrier logo showing

[MacMane]

i have service, but the tmobile logo isnt showing in top left corner...any suggestions?

 

[dZp]

i have service, but tmobile isnt showing in top left corner...any suggestions?

It's a known (and only cosmetic) issue :

http://blog.iphone-dev.org/post/188779017/3-o-fun

Update 2: Unlocked users on the 3G will probably notice that the name and/or logo of their carrier is missing, but they still have full bars and a signal. So far this seems to be purely a cosmetic issue and it doesn’t impact your signal or coverage. We hope to have this issue “fixed” when we release the 3GS compatible version of PwnageTool. This is very likely tied to Update #3…

Update 3: As of 3.1, the *.ipcc carrier bundles are signed, and you can no longer force tethering capability simply by crafting your own bundle. The good news is this obstacle can probably be overcome by virtue of the jailbreak. But so far that extra hack is not part of the PwnageTool custom IPSW creation.