I have never owned a phone, because I don't need it in my personal life. However it is time to start job hunting, and I have observed that companies expect you to submit a phone number with your application. For this reason I intend to buy a cell phone that I will use particularly for looking for a job. Let's say I get a phone number and I put this number in an online job application form or wherever else it is supposed to go, what will the company expect from this phone number? what are the type of calls that companies make to prospective employees? Do I have to carry the phone around and be available during work hours, or do I just need to look for missed calls once or twice a day? If I have a missed call, how fast do I need to get back to the company? Anything else I should know about phone calls and job hunting?
Most people calling about something important, like a job, will leave a message if you don't pick up, so you don't absolutely need to be available every time the phone rings. That said, for lower-level jobs with lots and lots of candidates, it's possible that they might just go to the next person on the list if you don't pick up. If you do get a message about an interview, you should respond as quickly as possible, certainly within 1-2 days.
Also, make sure your voicemail works if you're going this route - I once missed out on a job opportunity because my phone never notified me that I had a message.
Worth pointing out that many employers have rules about cell pones and personal calls, so reasonable recruiters/potential employers shouldn't require an immediate response to all calls. That being said, there will be some that will think less of you for letting your phone go to voicemail.
Two points that I would make would be, as said above, ensure that your voicemail functions, and you either get notified of messages, or check regularly.
Second, I would avoid putting your new number on any broadcasted application. If you make an application to a role, then that's fine, but if you're posting your CV on a job board/site, then I'd avoid it. I've found recruiters to be somewhat persistent and obstinate as a general rule (not all, but enough to get to me), and tend to call you repeatedly about opportunities which are not suitable, or not desired.
Most professionals will make some sort of introductory contact and try to find-out when is a good time to call. If possible, they'll try to respect and comply to your wishes. You won't be the first person to not be available while at work.
Hopefully, your phone came with voice mail. I don't always expect working people to answer their phones when I call and am usually surprised when they do.
Just carry the phone with you and answer it when it rings. If you're using it exclusively for that then you won't get any other calls anyway, so every call will be related to the job search and therefore important if you want a job.
It's pretty much expected for people to be immediately contactable these days, and frustrating for busy people if they're invariably not available. So best not to be looking for missed calls.