Over the past 40 years as teacher and administrator, I've discovered something really important about communicating with parents and students: do it often and don't wait 'til a child has done something bad.
For parents, create a consistent method of sending home information parents can use, not just random articles in a newsletter that they'll trash without reading. If you do that, you'll find that when you just have to send that note about Patty's recent behavior, you'll have a much more attentive and less defensive audience.
Early on, I began by creating little certificates that I sent home with kids for doing something really nice for another child or when their work was particularly good one week. I wrote a little note on the bottom, explaining what the "award" was for. Later, I tried sending home a little "comment sheet" with my students' weekly progress reports which allowed parents to ask questions make comments. I would respond to those comments and send them back to parents ASAP.
Creating email lists by asking willing parents to give me their email addresses took the place of almost all those methods once the entire district was "wired." I could do all of those things via email, and shoot a message to parents quickly. Some parents prefer email to phone calls, actually, because they're not put "on the spot." It gives them time to think and compose a response more carefully.
Most districts now offer Web sites that allow each teacher to have a page where s/he posts messages, homework and "blog" posts for parents. Some allow parents to view grades via a special "code" that will only show them their own children's grades. You can also have your own Wiki page to do similar things on Wikispaces, etc. Some teachers use apps as mentioned in another response to send texts to willing recipients.They're especially good for reminding parents of upcoming field trips or other events that they might otherwise forget.
And there are things like Google MeetUp that allow you to have parent meetings online as well--for free. You could even have homework help sessions after school on certain days for that. MeetUps are good for little workshops that teach parents how to help their kids with a particular project or to keep them up-to-date on things going on in the classroom. You can find sites that will allow you to have "chats" that don't require Web cams, too--Firefox and Chrome have chat apps that can be opened right from the browser. Or you can just have a blog page that allows parents and kids to post questions to you, so that you can answer them when you have time. But you have to monitor blogs and even school sites carefully. It might be a good idea to require all posts to be previewed first!
Similarly, you can have special Twitter, Instagram, Pinterest, Tumblr and Facebook accounts solely for parents and students, too, if you like. Again, they should be monitored and "filtered," but it can be done.
The simplest and most effective way I found to really communicate with students was to have each of them create a little journal that they were given a few minutes to write in at least once a week as "bell work." I responded to their entries and returned them either while they were working that day, or before the end of the week. Students really seemed to enjoy getting a personal, handwritten response from me about something that was going on in class. Some of the entries were heart rending, some heart warming. So that's something worth trying as well.
I hope a few of these methods are useful for you!