Just set up my SIP lines for our Office phone system (figured it's better if we are the guinea pig rather than the customer) So far they work. Just one thing I can't seem to get to work and it may just be something SIP can't do. I am trying to get EFA to work. Need to Flash the SIP and transfer the call out to a Cell Phone. Was assured by SIP provider this would work (before purchasing) but flash does absolutely nothing while on a SIP call. Yes I have EFA turned on for all the extensions because we use it just fine with our old POTS lines. Have quite a few Realtor's who use this to transfer calls to agent's cell phones when they are in the field. So want to make sure I can do it and not tie up 2 SIP Trunks while they are talking before I sell this stuff. Anyone have any thoughts on this?