The "+" is an international dialing code which will dial the international
access code (011 in the USA, 00 in many european countries) in a way that u
don't have to adjust it for each individual country (it is difficult to
remember all those codes).  The "+" sign avoids having to remember them and
will dial it directly/automatically for you.  It has its uses for some.
I believe that you have to set the dialing options not to add this "+" sign,
I believe you go to the Contacts view, then select an individual contact,
then Call Contact|New Call|Dialing Options and then uncheck the
Automatically add country code to local phone numbers check box.
Try it.
If it doesn't stop adding the + sign, the setting is somewhere else but it
can be turned off.
S