cmsmmsg.exeis a service belonging of the Broadcom voice modem services, pivotal to dial-up functionality for your PC when using this type of service.
This process is non-essential and should not be terminated unless suspected to be causing problems.
Non-system processes like bcmsmmsg.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that over time your registry suffers fragmentation and accumulates invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues