I’ve recently been using a Nokia E51 cell phone and found that the keys for navigating within applications – more specifically those within the image viewer, the Google Maps look-alike Nokia Maps, and the built-in web browser – were hard to remember. So I compiled a table of the keys assigned to some of the interactions available in these applications:
| Action | Image viewer | Nokia Maps | Web browser |
| Scrolling | Nav-Keys or keys 2,6,8,4 | Nav-Keys | Nav-Keys |
| Zoom in | 5 | * | * |
| Zoom out | 0 | # | # |
It appears that the image viewer is the application responsible for the confusion as the keys assigned to its interactions are inconsistent with those of the other two applications. That might explain why I keep pressing the wrong keys.
Proposed solution: The image viewer doesn’t need the number keys as an alternative scheme for scrolling, therefore those keys could be freed up for other commands. In turn, ‘*’ and ‘#’ would be available for zooming.
Advancing Usability 
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E51 which i bought is good but all the rubbers of on and off ,volume control buttons are real hopeless ,needs to be attended to tbis problem.