I am traveling around the US for 6 weeks or so and I am going to file my N-400 in the next few days before I go. As my mail will be on hold at the post office, I will not be able to find out my receipt number and therefore view my case online. Does anyone know if i call the Customer Service line will they tell me my case number over the phone? I would hate to miss out on a biometrics appointment!
Thanks!

If your bank provides scans of canceled checks, you can look at the back side of the check and perhaps get receipt number from there and use it on USCIS website.

What yu and dan said is correct, however, my bank scaneed the check in a way that the number was not visible.

and when I had the correct number it did not show the biometrics apointment nformation in the USCIS web site.

Is there somebody who can colect your mail while you go on vacation?

Be careful! We only got 1 week notice for our biometrics appointment.

Wow!!
It seems the N400 is moving so fast compared to the I-751! Thanks for your help guys. I think I will cut my holiday short!!I MUST vote this year!!!!

Us, too. We got the notice on 3/10 and had to go on 3/18.

I wouldn't rely on your online case status, even if you did get the number. In the majority of cases I have read about here, the info "touch" for the biometrics appointment does not show up on the online status. Personally, after my initial application appeared online, I changed my address, had biometrics appointment letter sent, submitted & received results of a service request, and had my biometrics done - with no touch's appearing at all online. Also, when I called, even with my case number, I was unable to receive info about my biometrics appointment - even though I found out later it had been scheduled & sent previously.

Do you have someone who could collect your mail for you - and watch out for an immigration letter?

Or alternatively, take your completed application with you, and mail it two weeks or so into your holiday (assuming you are holidaying domestically)?

Or, just mail it, collect your mail when you come home, and, if you find you have missed your biometrics appointment - do it as a walk-in as soon as you return. I unintentionally had to do this, as my appointments letter went astray in the mail, and by the time I found out when my appointment was, I had already missed it by three weeks.

Just FYI - technically, walk-ins (after appointment date) are accepted any Wednesday - but, you could try it at any time, and it is at the disgression of the office. I did a walk-in at 8.45am on a Friday - and was out by 9am.

HTH