There is one annoying issue with SMS: In my old phone (Nokia 6230i :-)) there could be several alphanumeric characters between the numeric characters, mostly used: the slash, as common in Germany. The FairPhone (or Android?) doesn’t allow that. So I changed this for several numbers.
But: When I get an SMS from a person where I removed the slash, and I try to answer, the message won’t be sent (message: failed to send the message, red triangle icon with exclamation mark). Then I copy it to a new message, pick the contact from the adressbook, the message will be sent and this answer appeares in the same (!) thread. But next time when I get a message from the person, the direct answer won’t work again.
How can I get rid of that behavior?