No Mail Alert when locked correct iPhone 3G

In my experience, this is not correct.
 PowerBook G4 17-inch/1.67GHz/2GB RAM Mac OS X (10.5.7) 7200rpm-100GB HD,  iPod w/Video 30GB,  iPhone 3G 16GB

Yeah, mine still beeps when I receive an e-mail.
Fujitsu Siemens Amilo Xi 2428 Windows Vista iPhone 3G

You need a clear line of sight to receive good coverage for Texts and Phone Calls. If you are in a basement full of walls and concrete, you may or may not get the best of coverage.
For eMails and network (3G) related, if you have a wifi station you can use this method instead along with a broadband connection.
You can however with forwarding charges, direct calls to land line.
If you dont get that many calls and can accept the forwarding cost as long as its within your minutes range.
Dell Studio Slim Desktop Windows Vista iPhone 3G