@Mir18 : As discussed in this and many other threads on the topic (search for number of rings voicemail, etc) the amount of time before a wireless phone goes to voicemail for most carriers in Canada is fixed at 20 seconds at the carrier's back end. If voicemail is turned off, this may be extended to as much as 60 seconds, but depends. Since most people have voicemail turned on, the 20 seconds is fixed and cannot be changed (Canadian carriers). (See post 3 of this thread and numerous other threads as mentioned earlier.)
I'm not sure why your particular situation has only 1-1.5 rings - perhaps something to do with a (poor?) signal in your area?
(There was a time a decade ago when phones were analogue when this could be changed.)