sms to/from spain

I tried to SMS a cell phone in Spain (it's either a vodafone or
movistar mobile, i can't remember which one) and although my verizon
wireless here in the US says the message was delivered, i haven't heard
back. Is it possible the message wasn't really delivered? Or that the
recipient can't send an SMS back to the USA from either of those two
companies? (vodafone or movistar). A separate message I sent to Germany
did work, but i've read in previous messages that there may be issues
with SMS to Spain. Thanks