ok i understand its calculated per day, which is best. i assumed each call was 16p for the first 3 minutes, and any successive minutes were reduced. Then a new call would start at 16p again for the first 3 minutes, and so on. Im glad I was wrong.

I'm curious about this callback feature. Does that mean everytime I want to make a call, I have to answer a call first? This appllies to world sims only, right? Or does Asda do that too? Ive never used SIMS like that before.

I have to decide now whether to use TravelSIM (which is around 20p/min to most European mobiles) + free incoming (and no setup), or desposible SIMS in each country.

Regarding selling SIMS, I checked that sub-forum forum and it's pretty empty. Do people really buy OLD sims?

Callback: This is how most international roaming SIMs work. National SIM's (like Asda) do not do this. When doing a callback call, in most cases, you will not notice anything too different! You dialled number as normal (either from the adress book or direct) and then push send/green/go. Then your screen will probably go blank and then your phone will start ringing a few seconds later. This will then be your outgoing call.

TravelSIM is not the only one. Have you seen the full comparison here?:
http://www.prepaidgsm.net/en/international.html

In case you hadn't noticed you will also find on this site the prices of SIM's in all the countries you want to go to. http://www.prepaidgsm.net/en/operators.html

Regarding your final question. Most people do not normally buy anything unless they see it as having value to them and at a good price. You say some of your SIM's still have $60 of credit on them. At the right price sure someone will buy it off you! However regarding some of your other SIMs (like national European SIM's), these are so cheap these days that it is little point in buying second hand. Also your buyer would have to be certain that the SIM's are still valid and still have the said credit on them!

hi i decided on travelsim because of comparison here
http://www.prepaidgsm.net/en/int/compare.html

Perhaps you know something about travelsim not mentioned there. It has the lowest per minute rate for outgoing calls (20p/min), no setup fee (unlike united mobile), free incoming from europe, and credit included in the initial purchase).

Maxroam has the same outgoing rate but with too many exceptions, and half the credit included in the initial purchase.

One thing i dont understand on either SIMSis the billing period? 60/60, 30/30. What does that mean?

The first number means the minimum charged time, the other for subsequent units. So per minute billing units would be 60/60, whereas 30 seconds minimum, then 6 second units, would be 30/6.

so then TravelSIM is the international SIM for me...

Good luck with the hectic travel schedule! Did you settle for Asda here in the UK?

Yes, i will get the ASDA SIM.

I also have an emergency international phone card (to use with payphones, and a toll-free number).

And finally, I use VOIP (like voipwisw), but one problem I noticed with Voipraider (which one of the cheapest I found online) is that I can't use my credit card to top-up credit. Voipwise allows me to use U-cash, and some other VOIP sites only say I can pay with Western Union (which is not going to happen).

I found Webacall, which has low rates (and they say I can pay with Visa), which makes sense to me. Why I can't pay using credit card on all those sites, I don't know.

I just topped up a VoIPraider account 3 days ago using a credit card. I don't understand what is happening with yours? VoIPwise is the same company anyhow (all part of Betamax) and can also be topped up by credit card. It may be country specific depending on where your card is issued. You could try and open a new VoIP account and specify a new country, though the country field is always filled in for you.

Yes, well my IP is still in Morocco, but I have tried putting in Canada, and UK and the options remain the same. I think the site is sensing my IP location and automatically disqualifying me from using credit cards. How stupid.

They just lost a customer.

Are you going to visit Poland?
So, does this card have a tool-free access number in Poland? If so, please tell me what exactly the number is - there may be some issues when calling it from payphones...

As to using SIMs from one EU country in another in order to use remaining credit - of course, it's more expensive than using local SIMs. However, the "eurotariff" sets an upper limit for costs of EU calls to at most 49 eurocents outgoing/24 incoming + national VAT(15-25%, depending on the country). So, I think than it's better (=less troublemaking) to you to use the remaning $20 on Vodafone Spain in another EU country than to look for a person willing to buy the SIM.
BTW, terms and conditions for roaming of some EU operators may extend the coverage of the "eurotariff" to some non-EU countries like Switzerland, Norway, Iceland etc.