Re: mmsc settings in spacebar,. In spacebar, there is a 3dots icon. After about twenty taps, it opened up with Settings and About. In settings, I entered Consumer Cellular (uses att network) android settings for the att mmsc network, i.e., MMSC -- url, MMS proxy, and PORT. Saving was confusing but just entering back key saved settings. Took a couple of instances to figure that out.
Then I sent a message and attached a text file to my samsung android phone. Spacebar said message was sent successfully (no message about unconfigured mmsc this time) along with attached text file.
But, message with attachment was not received on samsung phone.
Will keep messing with mmsc settings unless I hear of any other breakthroughs.
Note: my samsung phone uses consumer cellular sim card and attachments work fine. Sim card in pinephone was supplied by consumer cellar as a new line purchase so it should work. Phone calls and simple messages work fine. No mms yet.
tom kosvic