5060: This is the port configured in sip.conf
8088: This is the port configured in http.conf
10000:20000: This is the port range configured in rtp.conf
SIPML5 is a useful client for testing Asterisk but for real world use you will want to explore the different options and potentially make your own client.
Goto http://sipml5.org/ in your Chrome browser and use the live demo.