Poland

Orange
APN settings
 * username: internet
 * password: internet
 * APN name: internet

ERA
APN settings
 * username: erainternet
 * password: erainternet
 * APN name: erainternet

Heyah
APN settings
 * username: heyah
 * password: heyah
 * APN name: heyah.pl

Play
APN settings
 * username: (blank)
 * password: (blank)
 * APN name: internet

PlusGSM
APN settings
 * username: (blank)
 * password: (blank)
 * APN name: internet