title: Android, VPN, Asterisk communication
body: <p>I'm trying to write a voip app for Android, using the Android SIP API (Yes, I know this only works with some Androids with version 2.3). I want calls to be routed through an Asterisk server. The calls also need to be encrypted. A problem exists where Asterisk and the Androids need to be on the same subnet (otherwise no audio is exchanged). There is a nice blog post I found at <a href="http://blog.harritronics.com/2011/06/android-gingerbread-and-asterisk-pbx.html" rel="nofollow">http://blog.harritronics.com/2011/06/android-gingerbread-and-asterisk-pbx.html</a> describing the situation for those that are curious.</p>
  
  <p>I'm looking to setup a VPN solution as discussed in the article as I figure this could solve the NAT issue, along with encryption. My first thought was to use OpenVPN since there is a pretty active community and the software looks pretty nice. However, after further inspection, it seems that I can only have 2 clients active on the VPN server at any given time (for the free version). Each additional client connection is $5. In short, I'm wondering if a scalable free solution exists. I would like to be able to connect somewhere around 100 android phones to this VPN to communicate with Asterisk simultaneously.</p>
  
  <p>Also, I have done no VPN work previously. I'm wondering can I simply use the VPN configuration within the Android Settings? Or does there need to be an additional application? I saw that OpenVPN had a client solution for Android that only worked if the phone was rooted - this is not an option, as they are not my phones. Any advice would be greatly appreciated.</p>
  
  <p>Thank you!</p>