[u.masotti]

Firebird is supported by PHP, and Delphi for PHP can support it, but it can't out of the box.
What is not well documented about a Delphi for PHP to Firebird connection, is the fact that names of libraries can overlap in WIndows.
In this first post, I'd put a foreword to clarify situation.

PHP has a set of functions' libraries to "expand" his language. Well, in Windows package, php_interbase.dll is one of these interface libs.

For historical reasons php_interbase.dll (as released in Windows PHP package) searches for the Interbase/Firebird "compatible" client library named GDS32.DLL.

When all this started, some years ago, wasn't so problematic, because there were complete or almost good compatibility between client lib (i.e. gds32.dll) and any of two servers.

Some time after, Firebird and Interbase projects forked in a manner that Interbase newer version ( > 6.5 ) were no more compatible with newer Firebird's version ( >= 1.5 ).

So Firebird project changed GDS32.DLL name to FBCLIENT.DLL maintaing the possibility to install it as GDS32.DLL for older programs compatibility purposes. Note that the client library's interface to application program has compatible interface, but speakes to server in different language: this is why Firebird server doesn't communicate correctly with Interbases's client lib.

I did already post solution somewhere in the web, but I'll put in next post trying to write clearer.