I have tried multiple sim cards, including O2, which is locked to and not recognised. The black plastic parts have degraded and are very sticky.

Style: Bar
Connectivity: 2G, 3G, Bluetooth, Wi-Fi
Memory Card Type: Memory Stick Micro (M2)
Features: Bluetooth Enabled, Camera, Colour Screen, FM Radio, GPRS, Java Enabled, Music Player, QWERTY Keyboard
Model Number: P1i
Lock Status: Network Unlocked
SIM Card Slot: Single SIM
EAN: 5038262009283
Brand: Sony Ericsson
Network: O2
Model: p1i
MPN: SONYERICSSONP1IO2SILVER
Storage Capacity: 160 MB
Colour: Silver