Hi, I'm new to SIP and trying to figure out how everything works. I have an asterisk sip server. I have been able to set up two E-series phones to register there and I have been able to make Internet calls to each other.

Now my next challenge is to code something using the J2ME SIP API. I have downloaded the example, which can be found here.
When I try to use that, the calling phone displays 488 Not acceptable here. When I look at the asterisk sip debug information it shows 407 Proxy authorization required response to the INVITE.

What exactly is the problem and does someone know how to get around that?