Thanks for the reply. What we are trying to achieve is a hybrid VOIP setup which compose of landline and GSM.
We already have this VS-GWM400W and zoiper which we are using to call on mobile numbers.
We want to add our landline trunks to our current setup so we can have a local number per workstation and we can use the local numbers to call on mobile also.
I understand that with our current equipment we cannot do that but what can we do to make it work? We are also willing to buy an equipment with FXO interface just to make it sure that we can combine it with our current setup/configuration.