No, I haven’t messed up the numbers: there were models in the h5600. It’s just that they have been cancelled by HP (see for example this article).

There, however, are still floating devices around (see for example this eBay auction); I’ve also been offered one, which, being a die-hard gadget freak & collector, I'm really interested in. However, it just doesn’t see either the Wi-Fi, the BT or the phone unit at all – in Wireless Control, not even the icons of the first two show up as can be seen in here and enabling the phone results in a “a wireless radio must be attached to use the phone” message as can be seen in here.

The ROM version in the device I’ve been offered is 0.81.13 ENG, dated 08/13/02 (that is, pretty early, taken into account that it was only later that the first rumors on the h5600 series surfaced) as can be seen in here; the device has the GSM module, which has the version WGM_1310something as can be seen in here.

Therefore, if anyone has a h561x or a h565x, please PLEASE let me know :) I’d be REALLY grateful for any kind of help or information on this device. You’ll get LOADS of greetings and thanks in any “retro review”-kind of article I may publish on this rarity.

http://smartphonemag.com/forum/topic.asp?TOPIC_ID=19237

Q: Can I use my iPAQ 545x/555x as a phone? It DOES have a SIM slot! A: You can't. The 545x (and its successor, the 555x) only has a SIM slot because, back in 2002, it was planned to become a converged device. (This would have been the then-cancelled iPAQ 56xx series.) HP didn't redesign the 545x (and the 555x) after cancelling the 56xx series; this is why they have the (bogus and useless) SIM slot.