[nitrogen]

Are there apps available that show signal strength in real numbers (dBm) instead of "bars"?

[DrJokepu]

Not sure about Blackberry, but on Android: Settings / About phone / Status / Signal strength

[m_hughes]

You can always call this number from your iPhone: 3001#12345#

and put your phone in field test mode

(http://gizmodo.com/gadgets/iphone/iphone-field-test-mode-let...)

[rryyan]

Unfortunately this capability has been removed from iOS4: http://forums.macrumors.com/showthread.php?t=942533. Just confirmed it on my iPhone 4.

[brown9-2]

on Blackberry it's under Options, Status

[jarek]

And via the API: http://www.blackberry.com/developers/docs/5.0.0api/net/rim/d...

An app that instructs the user to pick up the phone and hold it to his head as he would while talking, records the RSSI over a course of a couple of minutes, then graphs or displays the results might be an interesting weekend project.

[SoftwareMaven]

You can do it if you've jailbroken. Haven't looked for non-jailbroken stuff.

On my 3GS, I can vary up to 20 dBm depending on how I'm holding it, how I rotate myself and/or the phone, where I'm holding it in relation to my body, etc.