Im looking to replace our current win2k3 server with SME. All things seem to be replaceable my only sticking points had previously been exchange and VOIP.
I have installed SOGo which seems to do the exchange stuff.
On topic we have a 3cx phone system running on the 2k3 server. I want to get rid of this.
We have a handful (

remote phones that are SIP handsets. They use static IP's currently (at the remote end) and we connect via SIP to the 3cx system and limit the IP that is allowed to login.
Other users use softphones (x4) and connect via the VPN as they are not on static IP
Plus we have 9 internal handsets.
We have 5 SIP trunks we use and a single ISDN2 line. This is connected via a Patton IP gateway
Main issues im concerned about.
1. We operate 4 different companies from our head office. I need different IVR's (I assume not a problem for these) but also need different hold music per trunk/handset.
2. Do i need to chnage the handsets (linksys / cisco handsets)
3. We often have to restart the phones that are using SIP remotly. IS this an issue with our current setup or am i doing it totally wrong.
4. Backup. I notice sark/sail has a Has a High availability option?
5. We also have 2 PSTN lines for Fax and Modem use. I know there is hylafax etc but is fax better or possible in Sail etc. Also is there anyway i can setup a virtual com port in windows to use the pbx for modem use.
Many thanks
James