The invention described herein provides a core modem assembly for a communication circuit that is well suited for mobile communication devices such as cellular phones, personal digital assistants, laptop computers, and hand-held computers. The core modem assembly comprises a baseband module, an RF module, and a socket connector that provides electrical isolation between the baseband module and RF module. The core modem assembly achieves a very small form factor and provides shielding between the baseband module and RF module. Further, the core modem assembly uses a “plug and play” design allowing late customization and interchangeability of the modules.