We have an Alcatel omnipcx. Within an couple of months some employees will move to an other building.
Of course these people also want to use telephones. I want to save money by making my own Asterisk PBX for this new building.
We will have an WAN connection between these buildings and calling with these people using the voip protocol.
Now my question;
You should be able to do this but note that each active conversation across your WAN link will use about 64KB/sec unless you use the G.729 codec available from Digium. That will reduce it to about 8KB/sec. To each of those add 10-15% for overhead.
If you also have data running acroos that line QoS becaomes a absolute requirement.