I've been playing with VoIP IP PBX solutions for a few months, but I'm trying to find a solution that will allow for the following:
- An IP PBX based in a data centre (where SIP trunks will terminate), idea being that the company has a single number for everything.
- Several(~10) IP phones in several offices (4).
- Each office has a standard SOHO router rendering most SIP-based IP handsets useless because of NAT.
- Each user needs an extension that they can take with them (soft-phones) or log into a phone with ("hotdesking").
IPSec VPN linking the office to the PBX is not an option here.
Any advice greatly appreciated.