I was put through the gauntlet of 4 1-hour phone interviews in 5 days for my current job...and I have to do plenty of phone interviews to hire employees.
1) RESEARCH. Know alot of specifics about the organization, the position, even a little bit about HK. Have questions ready to ask your interviewer, that will show how much you've thought about the job. You are showing them how well-informed you will be if they hire you.
The nice thing about the phone interview is you can keep all this printed out in front of you, with your web browser open as well

You can also take notes during the interview (if you want to bring something up again later in the interview, for example).
2) Be natural. Especially over the phone, it is tough to convey that confident, mature, affable persona they want to see. Just have a conversation, keeping your voice friendly+firm and your sentences concise. Inarticulate is esp. BAD on the phone, because there is no body language or eye contact to signal that it's time to move on.
3) On that note, be mindful of "the pause." Finish your sentences strong with a clear pause, and wait for that pause from your interviewer (who will be experienced at this). Sounds nitpicky, but there is nothing more awkward than constant interrupting.
4) Clarify if you don't hear something. It's a phone interview, the interviewer will understand.
5) Get comfortable. I did mine half-dressed in my bedroom, with coffee. Might as well take advantage of the situation.
This is a general suggestion, but interviewers love the "what's your one strength/one weakness" question. Be prepared; your weakness can be a passive aggressive allusion to a strength (For example, "Sometimes I tend to put work ahead of my personal life," really means that you are hard-working and dedicated. Or "If something is not getting done, I often take over to finish it" shows you have initiative and are results-oriented. Never incriminate yourself with something plainly undesirable!)
Hope that helps, good luck!