Saroj,
If you are simply looking to connect a phone to the A800 and make a call out over IP, you need only configure a static route with the destination IP address and add a * as the DN so this way any calls you dial will go to that IP address. You may want to make sure that you have the country set to 1, countrycode removed, areacode removed, ldprefix removed and intlpref 1 removed. These parameters are all found under the config sys prompt.
If you need further assistance you can contact me at mike_voip@hotmail.com to discuss my services.
thanks
Mike M
mike_voip@hotmail.com