unable to enter landline phone keypad touchtones after connecting on call

[http://dummy.us.eu.org/robert (Robert )]

This is the same problem I had before.  See Sonic trouble ticket #7202848.
It was working for a while, but this is again not working.  I was unable
to activate my credit card using the telephone keypad alone.

Even when I try to call a number, sometimes I have to dial twice for the
call to go through.  I.e., this is slightly worse than it was the last
time this happened.

The last time this happened, it was due to a firmware upgrade on the
Adtran ONT.  It's possible that Adtran messed up again.