Since Jaybird (Firebird JDBC driver) doesn't support Android, you need something more "hackish". Commercial solution would be using midware, eg RemObjects DataAbstract supports Android (pre-order/beta stage) and Firebird: http://www.remobjects.com/da/java.aspx
I'm not particularly familiar with Firebird, but my guess is the best approach would be to use a web service of some sort (RESTful?) which allows your Android client to communicate with the database. This is the solution that is typically used for most apps since you can't connect directly to the database from Android. It's also good from a design standpoint because your application does not depend on the underlying database itself, but rather the web service which acts as a mediator, meaning you can swap database implementations without impacting your client.
Since Jaybird (Firebird JDBC driver) doesn't support Android, you need something more "hackish". Commercial solution would be using midware, eg RemObjects DataAbstract supports Android (pre-order/beta stage) and Firebird: http://www.remobjects.com/da/java.aspx
I'm not particularly familiar with Firebird, but my guess is the best approach would be to use a web service of some sort (RESTful?) which allows your Android client to communicate with the database. This is the solution that is typically used for most apps since you can't connect directly to the database from Android. It's also good from a design standpoint because your application does not depend on the underlying database itself, but rather the web service which acts as a mediator, meaning you can swap database implementations without impacting your client.
You can try this Jaybird port for Android: http://sourceforge.net/projects/androidjaybird