This is by far the best "SIP" client you can buy! For those complaining about the pushed call not working right, all you need to do is increase ringing time on your voip server. I use asterisk. And i let it ring for forty-five seconds. The only improvement I would like to see is IAX2 support, but this is a sip client. And works very well. This app works very well and I recommend it. As far as G729a is concerned, try to buy a single licence for less. Its not so easy. I find that price very reasonable. If you use voip and ate not using this, your missing out.