I am using Q24+ and need A&D memory more than 3Mb

Hi,
I am using Q24PLUS for my product which has 1.6Mb of A&D memory, My purpose requires about 3+ Mb of memory. So I am facing memory shortage in the modem. Is der any product which is pin compatible and without changing the hardware I can just fix the chipset and use the same code with increased A&D memory.