Faxing Problem to just one User

I replaced a broken fax machine for our Cargo Office with a Dell 1815dn MFP. We can fax to all sites as before BUT not to New Zealand. What happens is after dialing the international tel# it rings, I hear the pitched tones, and the MFP displays says “sending page 1” and then it goes to “waiting to redial.” and the sent report says comm. error. I thought I needed to add the pause to the dialing scheme and it worked on the first day -I got the “fax completed” but now we are getting the same message “waiting to redial”. I checked with the New Zealand office and the fax is not in use and they don’t get an indication that a faxing is coming in. Plesae help….