WCDMA v. HDSPA v. UMTS

[inquisitor]

Originally Posted by caliston

Is there any difference in the SIM between UMTS and HSPA? I've seen people selling HSDPA SIMS but wondered if this was just marketing and they're the same as UMTS. By analogy that no special SIM is needed for EDGE.

No, there are no special HSPA-SIM cards. There is only a difference between plain GSM-SIMs and UMTS-SIMs (so-called "USIMs"). Wether a subscriber may use HSPA on a UMTS-network or not depends on what's defined in the HLR.
The main difference of GSM-SIMs and USIMs is the authentification-methods, since these differ between GSM and UMTS. However you can still configure UMTS-networks to accept GSM-autentification. Therefore in Germany you can access the T-Mobile and Vodafone networks even with ancient GSM-SIMs, whereas eplus and O2 insist on UMTS-authentifiation, so their customers need a USIM to register on the UMTS-networks. Since this is a question of network configuration a eplus/O2 subscriber with GSM-SIM can theoretically still access foreign UMTS-networks while roaming, as far as GSM-autentication is accepted.
Besides this relevant difference USIMs usually have higher memory capacity.