That's a very specific question with no easy answer, which is why you can't find any info quickly.
Where do you work? How many hours weekly on average?
Is there any employment contract?
You're paid a wage, I gather? How are you paid?
Is there an employment contract?
How long have you been at 29 hours per week?
Have you been on renewed contract? How long have you been there?
I'm here, so please take some time to flesh out your reply.
Robert, I don't think that there is a definitive answer to your question, which is why you couldn't find anything on your internet search.
If your employment contract is for part time and you are consistently getting 30 hours a week or more, then you can claim full time status from what I understand. But I can't tell you that definitively, nor are you getting 30 hours. Your employer my be under the impression that 30 hours a week is full time which is why you're getting 29.
Employers aren't obliged by law to provide benefits anyway, so I'm not sure what your "full time" status would accomplish for you other than a slight advantage in negotiating future severance pay in lieu of notice upon your termination.
An oral agreement is still an agreement, although it's harder to prove. If you think that your workplace values you and will offer you a full time contract given your time in, then ask for it. Then again you work at a call center, and telemarketing is notorious for being cheap with its employees.
I'm supposed to encourage you to accept my answer, but since I haven't really answered your question other than to say "I don't think that there's a law about that myself", you certainly aren't obliged to. Then again, this website has kids to feed too so if you've found this helpful then it's up to you.