Why do mobile phones require to "send" a dialed number?

In phone devices with rotary or touch tone dials you can just dial the number and the call will be made. It may happen that the call won't be made, or the user will dial a wrong number. However, the user intention will be denoted by dialing a number (Note: users on mobile won't dial, yet the word is a heritage from older technologies).

However, on mobile devices (including wireless phones) you have to dial the number then send the call. Sometimes you can pre-send the call (so to speak), clicking the button before the number, like in my wireless phone where you can press the send button before or after dialing, but you have to press it anyways.

I have some theories on the possible reason(s), dealing with avoiding accidental calls and acknowledging user intentions on mobile, while on older devices, picking up the handset would be indication enough of user intentions. However, I'd like to know the real UX and/or technical reason(s) beyond my theories.

Additional bonus question: is there a generic name in English for non-mobile phones?