After some trial and error, I got the popular Gizmo run on my PocketPC via the SJPhone SIP client (there is no native Gizmo client for PDAs). Read more for the instructions.1. Download and install your SJPhone client for either Pocket PC, Windows, Mac or Linux from here.
2. On PocketPC, click Options, Profiles, New. Call the profile “gizmo” and for ‘profile type’ use the “calls through SIP proxy”. Say “ok” on that window.
3. On the first tab of the ‘Edit’ window for the new gizmo profile, leave the default, but do check the first two checkboxes of “full address of”.
4. On Sip Proxy tab enter the ‘proxy domain’ as proxy01.sipphone.com with port 5060. Leave ‘user domain’ empty. Check, Check, uncheck, check, the next checkboxes on that same tab.
5. Leave the General and DTMF tabs as is.
6. On the STUN tab check the first checkbox and enter server address: stun01.sipphone.com with port 3478.
7. Click ok/apply to go away from these settings and then having selected the gizmo profile, select Initialize. Enter your SIP number for “Account” (not your username, but your actual SIP phone number, it is listed on your Gizmo personal settings too, it looks like 1747xxxxxxx), your gizmo password and for ‘Full address’ enter your number again like this:
8. Click ‘ok/apply’ again to go away from that screen, click ‘ok’ again, re-initaliaze the selected gizmo service from the “Service” sub-menu, and now you should be able to call out or get called.
9. [optional] You might have to free up ports 5060 (UDP) and 5004 (RTP) on your firewall and/or router if for some weird reason you can’t connect to the service.
Please note that SJPhone is pretty slow on PocketPCs. After you do a call, and you click on hang up, it will take a while to apply the hang-up. At that time, your PocketPC will appear frozen. It is not crashed, just frozen temporarily, because both the Skype and SJPhone clients are not really optimized for small devices (they are straight ports of their desktop versions). Just wait for it a bit and your PPC will come back to life soon enough.