A Garden Without Walls – SMS on XMPP (Jabber)

"XMPP is the open standard for messaging and presence." (https://xmpp.org). It is also known as Jabber.

While some companies (Google, Facebook) have (ab)used this free standard to make their own Walled Gardens, there is another group that is using it to move technology forward: JMP (https://jmp.chat)

JMP allows you to get a real phone number and use it for texting, calling, group texts, picture messages, and yes - it can even receive messages from short codes. You can use it with any XMPP-capable client on any device with an internet connection. You can also use it with a SIP client to make and receive VoIP calls.

Unlike Google Voice, JMP does not mine or sell your data. Also, you can use/buy JMP's service completely anonymously.