I want to use one SPA504G at remote office which has leased line data connection to head office. The traffic needs to go through router so, it will be different network. Remote office does not have any PSTN line and I want one 504G to station there as part of head office extension. If remote office user wants to call outside, it needs to come through head office PSTN line.
Head office has SPA9000 and 2 SPA400(one voice and one PSTN).
I saw in the forum that it is not possible to register SPA504G to SPA9000 if they are in different network. With softphone like phonerlite or X-lite works with different network. Is there a way to work for different network? If I buy additional SPA9000, will it possible to accomplish the requirement that I need.