on your ATA line menu set rynga register information

as following:

Proxy: sip.rynga.com

 Use Outbound Proxy: no
Outbound Proxy: sip.rynga.com
Use OB Proxy In Dialog: yes
Register: yes

Make Call Without Reg: no 
Register Expires: 3600

Ans Call Without Reg: yes 
Use DNS SRV: yes DNS SRV Auto Prefix: no  
  
Subscriber Information 
Display Name: your name

User ID: your rynga username 
Password: your rynga password

Use Auth ID: no 

set the rest as my blog on

http://blog.wenxuecity.com/blogview.php?date=201010&postID=11768