Does the smartphone reduce people's freedom from being on call 24/7?

I think not. It depends on how it's used.

I never liked using the phone that much in the era of the landline. Being a bit shy I was afraid I'd call someone at a bad time. Back then, I preferred to write letters and put them in the mail. I also favored face to face conversation.

Today, I have a smartphone, but it doesn't ring often as my connection to people tends to be through things like Facebook posts that aren't necessarily dealt with immediately. My phone doesn't ring often and notifications can be turned off.

I don't have to be "on call" all the time as my life tends to not have those kind of responsibilities. Sometimes I forget to bring my phone with me when I go out.

Ironically, I'm getting to like the phone more these days as voicemail and texting helps me get around my initial shyness. Voicemail means I can leave a message without bothering folks at a bad time.

My friends and me tend to text before we call. I often do engage in long phone conversations after being in touch by text and knowing the conversation is welcome.

I'm a deep thinker so when I do have conversations, they are often in depth and somewhat long winded.