Remote user phone access?

[cwhitmore]

I have five one man offices. They are using POTS single line phones via AT&T.
Our main office has an Avaya IP Office 500 v1release6. I have an extra SIP license since we moved from SIP to PRI. I'd like these remote offices to have ability to dial extensions in main office.
I'm looking at Asterisk or Lync as a gateway.

I want easy setup, softphones and cheapest solution. (we already have Lync running)
Will I need additional licenses from Avaya?
Suggestions on best way to allow ext calling for these users?

 

[amriddle01]

Why not just create a VPN and add an IP phone at the remote sites?

http://www.ipoffice.tel

 

[cwhitmore]

I already have a VPN connection to those sites. If I add VoIP phones I will have to buy licenses for each phone. I'd like to use existing licenses.

 

[amriddle01]

But using the existing SIP licences means way more work and complication, I'm sure the endpoint licences will make more sense in the long run

http://www.ipoffice.tel