Could someone explain what happened via telephony? Telegraph->Operator->Rotary->Touch-tone->Cellphone. It would seem everyone of these would be a next step in

Could someone explain what happened via telephony? Telegraph->Operator->Rotary->Touch-tone->Cellphone. It would seem everyone of these would be a next step in technology and protocols. Sending a text message via rotary phone is probably not possible. However, calling a rotary phone via smartphone should work. Is there a reason why newer protocols could not be implemented/enforced? Whereby email from proton to tuta (and similar new email services) it acts differently than when sent to the older version of email (current method).