I'll be showing my age and it's not completely like for like, but I had my first Gameboy (Gameboy Colour + Pokémon Gold, good times) on my 6th birthday.
I got a portable CD player Christmas of the same year. My brother received a Gameboy Colour on his 5th Birthday the next year, then we both received the Game Boy Advance Christmas of that year, when I was 7. My first phone came at 9, when I picked up Trumpet and had to go to bands and lessons outside of class, so I could call for being picked up and such.
I don't think 7 would necessarily be too early for a phone, particularly if it's a hand me down rather than brand new, based on my own experiences and those I'm seeing with my cousins. At that stage it's a music/internet/games/Netflix device rather than a phone, the only real difference I can see is that I needed the Computer, AND the GameBoy, AND the CD player (MP3 player by 10 I think) and a Phone to do everything, they get it in one.