Well, I have the Trophy and I don't think that I am sending that call back info. When I send a text to an email addie or a text to myself, I don't see the call back info. But when I am texting with my niece, I get that in her texts.
Now, after looking at the VZW web site there was the following question and answer on this issue (WP7 not referenced specifically):
Is there any point to entering my callback number when sending a text? My number will apparently show up anyway, correct?
The call back number is only useful if you have a call back number other than your mobile number. And having the callback number feature activated doesn't seem to go against the 160 character limit for text messages.
If you wish to turn this feature off follow this path:
Menu >> Messaging >> Settings >> Callback # >> On or Off toggle
So it is something that is being sent from whatever phone, and I do not see any setting in the WP7 settings to turn this on, not that I want it on. Are any Trophy's sending this info?