Hello,
I wrote the mentioned Article at
teltarif.de - Kommunikation ganz einfach and I own the UM +44/+1 SIM Card. If anybody is interested, drop me a private line (or e-mail) and I'll give you the +1 Number, to test it. As I'm based in Europe, I have no personal experience with roaming in the US or CDN yet.
The price list says:
located in the US or Europe, incoming calls on the
UK-number: 0,00 EUR/per minute plus one time 0,19 EUR per call.
located in the US or Europe, incoming calls on the
US-number: 0,19 EUR/per minute plus one time 0,19 EUR per call.
It's a UM+ Jersey number with a add on IMSI for the US including a SIM-Tool-Kit-Application to change the Identities if necessary.
When I make outgoing calls with the card it shows the UK-number.
If I'd be in the US, I could change the ID to show the US-number.