Moving a Phone to a Different Location

We recently began switching over to RC. I set up two Cisco SPA504G desk phones in my office and did a little testing. They seemed to work well. My business partner is going to be living in a different city for a couple of months. I gave him one of the phones to take with him. I thought he might be able to just plug it into the hotel network and use it. He has used the SoftPhone App in that location. To test that theory, I brought one home and plugged it into my router. It worked fine. He tried the phone at the hotel but it doesn't work. The four line-lights are amber instead of green and there is no dial tone. I am guessing the hotel has a firewall installed and the UDP Ports are blocked. Is that an accurate assumption? One other thing. The hotel has a VOIP phone system. He tried plugging into that too but no dice. He has a couple of laptops and has good internet service. I'm kind of stuck since I am in another city a couple of hours away.