Can send iMessages but not SMS from MacOS
I am running Mojave 10.14.6 on my MacBook Air. I can send and receive iMessages fine. I can also receive SMS messages but I am unable to send them.I get the red exclamation mark and the Not Delivered status. If I send an SMS from my iPhone, it shows up in the thread on my Mac. In the attached screen shots, the "Not delivered" messages were ones sent from the Mac; the successful ones were sent from my iPhone and showed up on the Mac. I have closed and reopened the Messages app; I have rebooted the Mac. I am not sure of the significance of the pink/orange status for the recipient.
The fact that iMessage works, and the fact that I receive SMS messages and can see the ones I've sent from my phone makes me think that all the configuration is correct. TIA for any suggestions.
MacBook Air