Potential Asterisk setup...over VPN, any help/suggestions?

I have a couple questions about running an Asterisk server on a LAN that requires remote users to login to a VPN. I am currently researching Asterisk for an overhaul of our phone systems.

The potential Asterisk server would reside in our main office. This office has a dsl modem that feeds a router with VPN enabled. We would want to accommodate approximately 30-50 users right away. We would probably expect a maximum of 3-5 simultaneous calls, with 1-2 being the norm. We want users’ extensions to be able to follow them, whether they are in the office on the lan or connecting from the internet. We also have 3 existing PSTN lines that we would want to have feeding into the Asterisk server as well.


  1. What complications should I expect regarding the VPN?
  2. What type of account would be necessary for directing outgoing calls to VOIP? (Vonage? Skype? Other?)
  3. Any other suggestions/concerns I might not be addressing?

(I’ve searched and read about connecting Asterisk to Skype and I realize this may be a very complex topic…)

Thanks in advance for any help!

Then you must have read that connecting to Vonage is impossible? (Well, not counting the method of connecting their ATA to an FXO.) Find a decent VoIP (a real one) provider is quite easy (you seem to be in the U.S.), so forget these two. A real VoIP provider allows you to connect via IP network, so no complications. But you still need to evaluate why you need to connect to a VoIP provider when you have 3 existing PSTN lines that you want to connect to Asterisk. Will it make more sense to go with one VoIP provider? etc.

VPN should not be any problem between offices with your type of volume. But roaming on the Internet can introduce quality issues.