Summoning Oozes (Monster Manual III, excerpted here) can use a Summon Monster spell-like ability - but they have no language.
How can they command the summoned monsters?
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According to the spell description of summon monster I, the creatures summoned attack the summoner's enemies automatically:
This spell summons an extraplanar creature (typically an outsider, elemental, or magical beast native to another plane). It appears where you designate and acts immediately, on your turn. It attacks your opponents to the best of its ability. If you can communicate with the creature, you can direct it not to attack, to attack particular enemies, or to perform other actions.
Since it doesn't speak, it can't do anything in that last sentence, so it can't give specific orders like which enemy to attack.
However, if it wants to call off the attack, summon monster I is dismissable (has (D) after its duration), so the ooze can de-summon the creatures at will.