It depends if you are in a two party or one party State in this regard. In a one party state as long as one party to the conversation consents (the taper) it's legal. In two party states both parties to the conversation must consent or its illegal.
“”In two party states both parties to the conversation must consent or its illegal.””
Now who on earth would dream up a regulation/law like that? Of course, the one doing the taping is consenting - what’s with BOTH PARTIES consenting?