We have a Canon B820 fax machine, which won't send faxes to a particular 0870 number. It works fine for all other numbers we use, and until a few weeks ago, it was fine with the problem number as well.
What now happens is that is dials the number, you hear the initial sound of it making contact with the fax machine at the other end, and it shows 'TRANSMIT' on the display. Then it sits there for a minute or so, before flashing up a message that alternates between the TX/RX number and 'START AGAIN'.
I've tried setting the TX rate to a lower value, but it didn't help.
The error report shows that 'TX function was not completed'; it gives a Result code of 'NG', followed by a '0' on the next line.
We can sucessfully send faxes to the problem number from a fax machine on a different line.