I am trying to set up modems at two sites. One site has a definity switch the other has IPO. The definity poles the IPO site it picks up but it looks like it the definity does not detect the modem. Does anyone one know if there is a special set up procedure on the IPO side? We use 4 digit dialing between the two sites. The modems work fine when I dial outside the switch and than back into the other switch.