ring alarm system, no cameras which monitoring do I,use?

Hi Guys, a UK newbie here.... I have set up my Ring alarrm system and it works fine, the questionis do i need to subscribe to one of the plans so that my alarm will phone my mobile should the alarm go off? It looks to me that the only option for phone calls is the protect plus, but I dont have any ring cameras on the system. Surely I dont have to pay for the PLUS monitoring just to get my phone to ring me when the alarm goes off, do I? Or is 'assisted monitoring' the way to get phone calls in the event of an alarm and does t cost money? Thanks for looking, any help wouldbe gratefully received. Eric