3 listed Open Tibia servers speak the 15.25 protocol, 2 of them answering right now. You need a Tibia client of that same version to connect to any of them.
play.capernia.com.br
BR15.25x15PvP
99.7%
uptime
play.soleraot.com
MX15.25x600PvP
servers.calmera.com.br
BR15.25x300No PvP
99.5%
BR
MX