We are trying to get Hylafx version 2:6.0.5 working in Ubuntu server (12.04).Installation and configuration went well. It detected our US Robotics modem.We are testing the fax send capability using yajhfc from another machine. When sending the fax its showing its in the running state and dialing but no
fax is delivered and it will terminate after the timeout period.

Also tried with sendfax command, it shows the fax requested id and other details but still the fax cannot be delivered.
We are not able to find any errors.

What will be the problem? Any idea ?

We are using a plain telephone line with no switches or other equipment.