[GadgetKen]

Bossman, looks like I was charged half a Euro each for 2 incomplete AT&T USA phone calls using the direct dial callback method that played a voice error message and 1.01 Euros for a successful T-Mobile USA outgoing callback call using the alternate *182*number# method. Was not charged (at least yet, don't know if some charges are delayed) for the BAL check to 1966 on either T-Mobile or AT&T...your mileage may vary. With any new mobile phone service, I always run tests even though I know I will get charged airtime....I figure it's worth a few dollars or euros to find out whether something works properly and if there are any peculiarities I should know before traveling.
Even though they charge for incomplete calls (I was warned about this before puchasing MaxRoam so it's no surprise) and the dialing method is cumbersome on my mobile phone, the rates will likely be well below either postpaid international roaming calls using a US sim chip or most hotel international landline call charges.
I hope they can work out the bugs with their new Belgian sim chips. In their favor they do answer questions on their online help system promptly, and they did replace their Israeli sim chips with Belgian ones promptly and without charge (more than I can say for my dead Yackie or BuyTel sim chips).