So... I have customer who wants a loud bell to ring whenever ext 321 rings. I have an MFM - I am thinking I would just tell it it covers for 321 and a bell connected to the MFM would ring? Are there any specs on the bell or is it anything that plugs into an RJ11? I have never done this before and the feature reference guide doesn't really help. Any programming and/or hardware recommendations would be useful. Thanks!!