While an 18M version A can be upgraded to version B, it is a costly upgrade as it requires replacing the module's internal motherboard.
Due to hardware limitations, A units may not see all the features available to B hardware, hardware A modules are and will continue to be supported by the latest firmware versions.
To identify the differences between the 18M hardware A and B versions, please reference the following support documents: What is the difference between 18M hardware A and 18M hardware B? and also Hardware versions and what that means for me.
Contact support for more information at email@example.com.