Need Phone # for 24hour Support! No answer!

We have a 24 hour seven day a week support contract for our Informix Production server. How ever, whenever I call the 800-274-8184 support number they say the office is called. Help! What am I doing wrong? Is there another number I can use? Is there a special passcode to get through? Any replies are greatly appreciated as our Production system is DOWN and there is no hope getting it up without support. Thanks in advance.