Data call is connected (handset displays a non-blinking "Data Call in Progress"), but nothing seems to happen.

There may be a problem with your networking properties or a problem at the remote end. For example, if you are using Dial-Up Networking to connect to a LAN or to an ISP, you should verify that the Networking properties are set in accordance with the requirements of the LAN or ISP. At this point, you should contact you ISP or remote end administrator.