A little update with some corrections.

Outgoing SMS seem to work to all operators I've tried with, i.e.: Wind, Vodafone and 3 in Italy, Orange in Poland, Vodafone New Zealand and Travelsim (Estonia).

Incoming SMS work with NONE of the above mentioned operators. The only SMS I received was the one sent from mobiSMS. I never received SMSes from Truphone itself, which I should receive, as stated on the guide, every time I connect to a roaming network to get information about rates.

I received a call from 3 ITA (our friend AndreA) and it was perfect, very good voice quality. I also tried to call him before and the phone rang but he was busy. So there seem to be no problems with voice calls (both incoming and outgoing), and outgoing SMSes. While incoming SMSes don't work at all.

Thanks to our friend KiwiSteve I also tested SMS sending to 2degrees, the new NZ operator, but it failed.

Truphone's SMSC is +316540940903 which seems to belong to Vodafone Netherlands, by the way...

What is SMSC?

Look at it as a server that relays mail, like an SMTP server for mail, an SMSC relays SMSs.
It accepts SMSs and routes them to the appropriate servers for delivering it to the recipient.

This explains it better than I can...
Short message service center - Wikipedia, the free encyclopedia

Thanks for the explanation :)

BTW I am in the Netherlands right now, and Truphone treats roaming as "local" even though I have a USA number. It also says vodaphone.nl in the APN, so I guess it does use something natively Dutch. In Canada it always mentions "roaming" when I use wireless internet.

That is why I asked about SMSC :D

Anyone is able to receive SMS on a Truphone sim? From Italian mobiles it's still impossible to receive any...

I just tested sending an SMS from my Google Voice account to my Truphone number, no problems there. I'm in the Netherlands right now.

It would be more interesting to test from some normal sim card. Also from MobiSMS it works, but from all 4 Italian operators, Travelsim, New Zealand operators and one Polish operator I received nothing...

I will be roaming in Macedonia soon, with the majority of calls to Croatia. Both countries are not on the list. Anyone knows why ?

From a Dutch mobile phone (T-Mobile) I receive SMS without problems :) Not sure why it doesn't work for you?