Even though the 5510 was revolutionary, it technically wasn't the first phone with an MP3 player. The Siemens SL45 introduced this feature almost 4 months before, in August 2001! : r/vintagemobilephones
SIEMENS SL45 - Petra Riedmueller
Siemens SL45 was the first mobile phone with memory expansion and an MP3 player, which debuted in 2001. I have one with 32… | Classic phones, Phone, Old cell phones