Quoted from above PDF 1.2.1: > FinCEN’s regulations define the term “money transmitter” to include a “person that provides money transmission services,” or “an

Quoted from above PDF 1.2.1: > FinCEN’s regulations define the term “money transmitter” to include a “person that provides money transmission services,” or “any other person engaged in the transfer of funds.” A “transmittor,” on the other hand, is “[t]he sender of the first transmittal order in a transmittal of funds. The term transmittor includes an originator, except where the transmittor’s financial institution is a financial institution or foreign financial agency other than a bank or foreign bank.” As long as Signal or its servers don't itself take part in transmission (which they wouldn't as long as the Signal app acts as a real user-side wallet and client) or trades/converts assets on behalf of the users, they should be exempt of this regulation. Say what you want about this regulation, but so far I find it reasonable; as long as you as a business don't touch crypto assets or private keys either as issuer, key custodian, or transmitter but simply provide the wallet/node software, you're in the clear. Unless Signal acts in bad faith, I see no way they would fall under scope of Fincen regulation wrt MobileCoin. IANAL etc.