Depending on the type of PBX, you may need to use an outbound proxy.
In the case that you need it , outbound proxy is : voip.3starsnet.com port 5060
Click "Manual Configuration”.
If you do not know the type of your account, select SIP.
First you need to enter a name for your new account in the "Account name" field.
Enter any name that will help you to recognize the account.
Then fill in the account details in the appropriate fields.
Host is : voip.3starsnet.com :5060
outbound proxy is : voip.3starsnet.com port 5060
login is your sip username (telephone line username)
password is your sip password (telephone line password )