before anyone can make any helpful recommendations. What kind of information do you wish to share amongst your branches?
The simplest way is email - why can't you communicate in that way? If you are sharing confidential information you could set up a web site, and have your branch managers login to special areas - one for each branch. Then you could put whatever content you want each manager to see in his/her secure area, and nobody else would see it. I did this for a company in Hong Kong, and it worked very well - they had around 30 senior people, all with a private, secure section of the same site to themselves.
Tell us what kind of communication you need, and we'll help if we can.