i've had the same problem a few days ago (i've called italian and foreign sims):(

Having just placed some test calls in Germany, here are the results, according to which UM+ does only work on a single German network (T-Mobile) flawlessly:

T-Mobile
callback by Call: +
callback by USSD: +
availability: +

Vodafone
callback by Call: - (call is being blocked, but no callback follows)
callback by USSD: +
availability: +

E-Plus
callback by Call: - (call is not being blocked, but announcement "barring service activated")
callback by USSD: - (USSD command remains without confirmation "Thank you for your request")
availability: +

O2
callback by Call: - (call is not being blocked, but announcement "number temporarily unavailable")
callback by USSD: +
availability: +

CLIP doesn't work for outgoing calls at all with any German operator.


Has anyone tried UM+ in Mauritius yet?

The last news from France with my um+ (Grenoble, Rhone Alpes region)
-roam on Sfr, Orange and rarely Bouygues
-call by callback: quite well (um+ shown the caller, but i can see um+ number on my italian sims:confused:).
Call quality is perfect (incoming and outgoing)
:D

I think it would be interesting to enter incoming calls' numbers on 'My account': now we can see only outgoing calls' numbers

A couple of days ago, I thought that AOL offer had at last expired, but it's still (or again) there; maybe it was something to do with my cookies

Today I arrived in Mauritius, where UM+ works comparably fine:

Cellplus Mauritius
callback by Call: - (call aborts after quite a while without any callback)
callback by USSD: +
availability: +
outgoing SMS: +
incoming SMS: +

United Mobile - call set up rate
 

Check that I understand this correctly. I am going to be calling back to the USA from Portugal with my UM -44 number.
Charge is 40c set up rate for each call then 45c each minute.

The website says the outgoing call set up rate is 40c (one time). What do they mean by "one time"?

They mean that the first minute costs 40¢ (setup) plus 45¢ (air time) for a total of 85¢. Each additional minute costs 45¢ so a 2 minute call costs $1.30 and a 3 minute call costs $1.75, etc.

New data offer http://www.pitelefonia.it/p.aspx?i=2219102 (0,95 euro per Mbyte)

UM+ doesn't work in Trinidad, I got a ..Service not available.