21910: Invalid From and To pair. From and To should be of the same channel.

From and To in the message send should be of the same channel.

From=+120221592555 and To=whatsapp:+120221592551 From=whatsapp:+120221592555 and To=whatsapp+120221592553

Send message with the same channel. To and From have same prefixes or both without prefixes.