DND is just the name of a feature (that doesn't do what you want). What are your actual requirements?
For example, suppose you wish to dial (from a phone attached to the OBi) a code that causes subsequent incoming calls to not ring the phone but be sent to voicemail, and have another code that restores the original behavior. Change Star Code Profile A -> Code7 to *72, Cfwd All, set($Cfa,1) Then, manually set CallForwardUnconditionalNumber to the number of a voicemail service. If you want your main GV account to get the voicemail, you will need to send the call via another service. Once set up, you would dial *72 to enable the feature and *73 to turn it off. If you want the original called ID to be passed to the voicemail service, you will need to send the call via a provider that permits spoofing within the OBi's limitations (Voxbeam, Flowroute).