OP.
I have worked in a call centre and they truly are 21st century sweatshops.
However, there are ways around this.
If it really is only 1 minute to your break, just enter the break code in your phone - but, you will need to return from your break 1 minute "early" ie. ensure you only take your allotted break allowance.
More than a minute or 2, as poster upthread suggested, take the call then speak to Team Leader to let them know and is it OK for you to take break now or do they want you to wait until x is back?
Do you have a "comfort break code" ie. code you input if going to toilet? (Oh yes, these are timed).
If so, you could input that for the spare minute - nip to loo quick, return to desk and input tea break code.
It is madness but, unless you have worked in a call centre, you really have no idea how closely staff are monitored.
Speak to some of the "old hands" discretely and, as with any job, they will teach you some of the tricks of the trade - but, don't take the p* - you will be found out.
Good luck.