There are many many reasons why this may not be happening.
Very few Telco's will provide a default name outbound and require the PBX to provide the name.
Depending on the hardware and software that you have, you may not be able to send names, may only be able to send desktop names or in a best case, you can send an alternate name via the department field.
To advise you better I need to know:
3300 software revision
Hardware connected to PRI
Telco provider (or country)
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Occam's Razor - All things being equal, the simplest solution is the right one.