|We are putting the same ip phone system in a remote office and need internet access on the 192.168.43.0 network to create an office to office VoIP network|
We tried this with a remote office at another university. Our office there used ADSL for internet access (it's only a 2 person office). ADSL does not (here anyway, it may differ where you are) allow for VLAN tagging or QoS across it which was an issue we circumvented using a VPN tunnel.
BUT and I stress that but, it never worked properly and in the end, we just got the local telco to put two digital lines in that office.
Your best bet, if you feel you have to have VoIP in both locations, would be to use a local VoIP provider on one end since competition for bandwidth on ADSL (or cable........whichever provider you use) is fierce and most ISP's oversubscribe their segments to make more money. Without QoS you have to compete with all the bandwidth hogs running Point-to-Point software dealing in illegal music/movies/software etc, and it's a losing battle.
As I said, in the end we gave up on the idea because of the constant hassles trying to have enough bandwidth to make it work over public links.
FWIW, all our other intersite links are direct and we VoIP over them without issue because they're not public and we're able to do QoS.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.