FonoSIP siphon voip configuration help.

Siphon Settings

Username: 812345
Password: password
Server:   fonosip.com

all other options leave as default 
or blank as shown in the settings 
screenshots below

For best call quality also enable 
Codec G729 on "phone settings" -> 
"codec" -> "G729"

Screenshots

optional

fonosip siphon skin