I once worked in a call center and was responsible for making the calls to French-speaking Québec.  Although I had just graduated with a bachelor’s degree in French, I was a bit intimidated the first time I had to make a call.  I mean what was I supposed to say to these people??? And the fact that I had to remind them of their debts and their obligation to pay them ASAP was not so comfortable either. In any case, I quickly got used to making the calls. I thought I would share this experience with all of you since you may just have to either answer a phone or make a phone call in French some day.
So, if you ever do have a need for French phone vocab, well, here are some ideas:
First of all, use ‘vous’ if you’re not sure who is on the phone. This is the way the phone was answered at my university office in Paris: ‘
Central College, Bonjour!” Now, I find that really simple and it works quite well for any type of office really. You could say, “(Company Name), Bonjour!”. But, you will probably have to add who is on the phone…in other words, your name. So, you could say, “(Company Name) Bonjour! (Your Name) à l’appareil“.
If you are making the call from your office, you will probably want to say something like this: “Bonjour, pourrais-je parler à (person’s name you want to speak to)(Could I speak with…?) or “Bonjour, je voudrais parler à (person’s name you want to speak to)” (I would like to speak with…). When they ask you who’s calling (C’est de la part de qui?), you can say: “C’est (your name) de la part de (company name) à l’appareil”. They might tell you “Ne quittez pas” which means to please hold or “Je vous le passe” which means I’m transferring you. If you’re not very lucky, the line might be busy for the person you want to speak with and they’ll say, ‘La ligne est occupée”. If the person is not there, you can ask, “Pourrais-je laisser un message? (Can I leave a message?) …but then for the message, you’re all on your own! ;)

Now, if you are in a private home, you can just answer the phone by saying Allô? That’s really simple!