That is my first thought. If I config. FDN to 0 or to an ext. when I call the 3904 set it will forward the call immediately to those respective numbers, but if I turn off FDN I get the fast busy. I was hoping someone might be able to tell me with regards to FDN, FNA, CFTA, HTA, FNAL, CFNA, Ect... should be allowed or not with this set configured for internal calls only. If this is again too vague, then I'll try to do more research or try to get the data posted.
Thanks,