Translation:They will have called all the companies.
In line with Brilqntin and t.winkler, WordReference's entry for "llamar" and "llamar a" seems to make a subtle distinction to the word with and without the addition of "a." Without the "a" it means "call" as in "name" and with it, it implies the type of calling you would do with a telephone. The WordReference entry for this word is below:
When I posted the comment above, I didn't know as much about Spanish as I do now. In fact, I may or may not have even been aware of this thing called the "personal 'a,'" but have since done some reading on and practicing with. Heck, now that I think about it, I even wrote an article about it. (Nothing like trying to explain something to others to understand it better.) If you'd like to read it, click on the link below:
With regard to the comment above, whether you think of the "a" as something you automatically add after "llamar" (conjugated or otherwise), or you think of it as necessary for "personal 'a'" reasons, it makes little difference. After all, when you call by telephone (or through some other method), are you going to be calling an inanimate object? No. You're going to be calling a person and more often than not, someone you know very well. Either way, it ultimately calls for the use of the personal 'a' no matter what you want to call it.
According to information I found on a web page, Monica590636 appears to be correct. An abbreviated excerpt from that page is below:
The future perfect is packed with promise. Use it when the outcome is almost certain. This tense lets you
• Express what will have happened by a given time in the future:
Ellos habrán llegado para este fin de semana.
They will have arrived by this weekend.
• Express probability or conjecture (when a slight doubt exists) of a recent past action:
Ellos habrán llegado.
They must have (probably have) arrived.
To view the full page, visit
Apart from the fact that "would" is the conditional, not the future, you have made a common mistake of using "of" instead of "have" to form a perfect tense.