On Android you will have to use the excellent SipDroid application, freely available via Google Play.

More specifically,

1. Start the SIP Droid Softphone
2. Go to Sip Account Settings
4. Fill in your information as obtained from Control Panel - My Services:
• Authorization User Name: YourUserID  
• Password: YourPassword
• Server: YourDomain  (e.g., toronto.ezvoip.co or replace "toronto" with your city)

Enjoy! (Album)