Symbian Signed For Testing Your Application
Applications that use only the "user grantable" capabilities can be self signed for both testing and distribution. However if your application needs more sensitive capabilities, you will sign it using a Developer Certificate during testing and development.
A Developer Certificate will limit the the devices onto which your application can install (by IMEI). So if you wish to deploy your application to a group of testers, you will need to know the IMEI number of their devices. You can easily find the IMEI number of a phone by using the *#06# shortcode on the handset.
For larger test deployment (up to 1000 devices) you need to purchase a Publisher ID and verify your Symbian Signed account (without the publisher ID you can only request 10 IMEIs). Note that you will need a Publisher ID anyway, in order to Symbian Sign your application for distribution.
Instructions on obtaining Developer Certificates are provided in User guide: Symbian Signed