Why is it téléphoné and not téléphonée?

Question

- Est-ce qu'elle a téléphoné à ses parents ? - Oui, elle leur a téléphoné hier.
 
Why is it téléphoné and not téléphonée?

Céline Pickard · Accepted Answer

Bonjour shiloh,
The lesson states the following:
"When you replace the direct object by a direct object pronoun (le/la/l'/les), it moves before the verb. That's when the past participle has to agree."
and
"This rule doesn't apply to indirect object pronouns. For those, there is never any agreement."
In the sentence above, "à ses parents" is an indirect object. Therefore, even if you replace it by the indirect object pronoun "leur" (= them), the past participle "téléphoné" will not agree as it is not a direct object pronoun.
 
INDIRECT OBJECT PRONOUN = no agreement:

J'ai téléphoné à Marie -> indirect object
Je lui ai téléphoné -> indirect object pronoun

DIRECT OBJECT PRONOUN = agreement:

J'ai mangé une pomme -> direct object
Je l'ai mangée -> direct object pronoun

I hope this is helpful.
Bonne journée !