When the OS boots, it checks the system registry for the following key:

HKEY_CURRENT_USER\Software\Microsoft\SMS\TextShared 

This key contains a flag that specifies whether EMS processing is enabled on the device. EMS processing is disabled by default, however, you can enable this support yourself.

• Register the COM component's GUID by creating the following registry key, and giving it the following name/value pair.

  HKEY_CURRENT_USER\Software\Microsoft\SMS\TextShared
      DWORD : EMSHandlerInstalled = 1

 Remarks

EMS is defined in 3GPP Technical Specification 23.040 "Technical realization of Short Message Service (SMS)". It can be obtained from this website http://www.3gpp.org/ftp/Specs/html-info/23040.htm.

 See Also

Concepts

Short Message Service (SMS) API

Other Resources

IMessageFormEx
IFormProviderEx