Hi freind
I tried with the above settings still remaining same.Here is the settings I put

SIP address : 1234@sip.voipdiscount.com

Password : xxxxxx

User name : 1234

Transport : Automatic

Outbound proxy : (left blank)

Port : 5060 ( Also tried with 3478)

Discover public address : ON

Loose Routing :Off

Keep alive mechanism : Automatic

Keep alive period : Automatic

Auto detect STUN : ON

When calling I can hear the beeping sound.But after pick up nothing hearing.