Of course there are opportunities if you want them. Phoenix, like any major metropolitan area, has under-served communities. A big program that a lot of students like to participate in is H.O.M.E. which is a program where you help run a clinic for the homeless alongside upper-classmen and physicians. There are two or three different clinics with different populations they serve that are part of the program. Also, there's DOCARE. I'm not sure what all they do on-campus, but I do know that they do care. Also, a lot of the "just for residency" programs do a lot of community service as I think it's pretty much like a sorority/fraternity where your group has to do some community service to maintain official standing with the school. So you'll see a lot of these clubs helping out with various walks to cure X disease, running booths to promote awareness of or screen for X disease, etc. Then, the school is involved with a program called TOPS where students and physicians go to area high schools to perform sports physicals on students in low-income areas. So, for MS1's it's actually a requirement to do this for four hours and, coincidentally, that's what my colleagues and I will be doing all day this upcoming Saturday. Also, the Interdisciplinary Healthcare "class" requires you to do ~4 hours of community service at some point during your MS1 year in order to pass. Also, the school runs high school preview opportunities where current high schoolers interested in the healthcare field (or who have been drug here by their teachers) attend presentations and workshops done by various programs on campus and students who either volunteer their time or get paid work-study to do so. Finally, you can always pad your CV and start something yourself.
So with all of these opportunities, the student government also keeps track of "TOUCH" hours which are essentially what they call your volunteer time. It's some sort of volunteerism competition, more-or-less, between the various COM's and as far as I can tell, AZCOM typically kicks butt (I guess it's the by-product of having large classes with large numbers of Californians and Utahns/Utahans 😉).
Pretty much, if you find you have the time and desire to volunteer, there most definitely are ample opportunities to do so.