I have an old AVAYA v3.0 PBX with 16 wired analog phones in the office. There is no attendant installed. All phones are ringing at the same time. I need to add just one extension for a remote user via the Internet (in a different state). High speed Internet is also available on both sides. Do I have to replace the whole system for it to be IP capable or is there a solution for connecting one of my phones via the gateway?