Are encrypted phones illegal?

Are encrypted phones actually considered illegal? I've heard mixed opinions on the matter, and I'm curious to understand the legal implications of using encrypted communication devices. Are there any specific regulations or laws that prohibit the use of encrypted phones, or is it more about the intent behind their use? I understand that encryption can be used for both legitimate and illegal purposes, but I'm specifically interested in the legality of the phones themselves, rather than the content they may be used to transmit. Can you provide some clarity on this topic?