Suresh,
You can find all this information in the A800 reference guide still available on quintum’s web site.
If you do not know the password, you will need to reset the unit to factory default. This will wipe out the entire config, except the IP address information. You need to do this from the boot up screen using a pc connected directly to the unit.
If you need specific assistance on this, please contact me directly at mike_voip@hotmail.com
Thanks
Mike
mike_voip@hotmail.comm