At work we currently have 2 separate networks, 1 for our phones (192.168.2.x) and 1 for the computers (192.168.1.x) that share 1 router (Draytek 2820) for internet access. We have a typical small business network with all of the computers connected to a switch, the DSL router connected to the switch, and the DSL router acting as DNS server and gateway. The phones are connected to a separate switch, the LAN interface on the PBX (an Epygi Quadro 6L) is connected to the switch and the WAN interface is connected to the DSL router.
Because of some minor problems we've been having I thought it might be a good idea to have a separate DSL tail for data, so in the case of the voice DSL tail going down it doesn't mean that we can't access email as well. If we go down this path it means that the voice DSL tail only gives us access to the SIP servers our calls go through.
We are currently sent emails when a voicemail is left (the PBX does this) but obviously if the PBX can't access our (external) mail server anymore then that's going to be a bit of a problem.
What would be the best way of re-arranging the networks so that we could have separate DSL tails for data and voice but still be able to receive email notification of voicemails? I'm open to anything - setting up a proper router/gateway type server, hosting mail internally, separate networks by VLAN etc.