Duplicate Line:  iPhone SMS error "Not Delivered"; however recipient successfully receives message

bordelais

    Starting today, my iPhone 7 is getting "Not Delivered" error messages on all SMS messages sent from the iOS Messages app.  The SMS messages, however, are successfully delivered to the recipient.  I see the outgoing messages replicated to the Samsung S7 device in the native SMS app.

     

    I've power cycled the iPhone, but the errors are persisting.  Any advice/recommendations?

     

     

     

    Here is my DIGITS setup (if that helps):

     

    iPhone 7 (10.2; T-Mobile variant)

      - Duplicate Line SIM

      - DIGITS App:  Digits Virtual Line Active, Linked Account Line Active

     

    Samsung S7 (6.0.1; T-Mobile variant)

      - Original Line SIM w/ multi-line enabled

      - Digits Virtual Line Active, Linked Account Line Active

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