A novel and useful apparatus for and method of communicating time related messages between multiple devices wherein each device operates using a different time base. The invention can be applied to multi-mode cellular handsets that implement multiple radio access technologies (RATs). Messages communicated between the RATs are time synchronized using a common time base that is shared among all the RATs in the system. The creation of the shared time base is based on an interrupt signal referred to as a "sync event". The interrupt signal is generated by at least one of the devices and received by all the other devices. The local time is stored in a snapshot register and is used by each respective device as the basis to perform conversions between local and common time, common time being the time base that is shared by all the devices in the system. This `synchronizes` the devices since they all took a snapshot of their respective local timers at substantially the same time.