If you want make secure phone calls, these phone Misers look pretty good. A little pricey, but can you really put a cost on privacy? Yes, $295 for one, and a second for $195 (you need 2).
For absolute secure phone calls, The Secure-Phone-Miser is a secure telephone unit that utilizes multiple unique encryption algorithms with 1 million user programmable codes to secure voice communication links and provide maximum security. The Secure-Phone-Miser provides privacy for confidential conversations even if a line is electronically tapped. Eavesdroppers will not be able to decipher the contents of the secure phone communication link. The Secure-Phone-Miser can secure multiple phone links for conference calling. A maximum of ten (10) links may be secured simultaneously. Connects between handset and your phone base.