Hi Chris
I have checked our local phone listings for your friends daughter and there is not one listed in the Jerrabomberra area and only 6 in total for all of the Canberra area but none have the initial H.
I'm not sure which parts of the phone number are US dialing codes and which are the phone number so I didn't try that and it is 3am over there at the moment.
I did find one Helen with the surname you think is the daughter's name on Facebook (there are not many) but it doesn't tell me where she lives, so maybe have a look and see if you recognise the face from photo's your friend put on her facebook page.
Sorry I couldn't be of more help, I hope your friend gets in touch soon, she is probably having a great time travelling and unaware that there are great friends like you who are worried about her.