I have a main site and then an ESS that is connected back. There are digital phones at the ESS site and when we do 4 digit calls between locations we are getting one way talk path. The main site end doesn't hear the ESS end. What would be causing this.. the link between the sites is a 100mg connection and soley for voice. The only difference is the ESS site uses TN2302 medpro and the main site is using tn2602. Other than that things look healthy.