2 different texture packs.
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Most servers use the big one (v5, ~25MB), unfortunately its legality is confusing.
See this topic: http://openarena.ws/board/index.php?topic=2876.0
And this one: http://openarena.ws/board/index.php?topic=3682.msg31591#msg31591

About the v4, see this topic: http://openarena.ws/board/index.php?topic=1968.0

Of course, best solution is to replace every texture properly. See: http://openarena.ws/board/index.php?topic=2823
This pak is also hosted here: http://download.tuxfamily.org/openarena/files/pk3/missingtextures