I am currently and have been using a phone line to send/receive faxes, my DSL connection, and for dialing into external devices for daily meter readings with a 56k modem. I have filters on the fax and 56k modem. Prior to me purchasing a new Linksys business router I did not have any issues with connecting to the external devices on the 56k modem. Now that I have installed the new router the modem gets to the handshake and then it sounds like it hangs up. I know that it is an internal problem because others outside of the office are capable of connecting to the meters to get the daily readings. Does anyone know anything about 56k modems and having potential issues with a router that would be behind a DSL modem? Also I can still send/receive faxes fine. I have tested it in other phone jacks as well as multiple 56k modems to no avail. Please help.