As for calling techniques, let’s start with bugling. Every new elk hunter owns a bugle; whether or not they know how to use it properly is another thing.
Years ago, the bugle used to be a great way to bring elk in close. Bulls were accustomed to other bulls “bugling” their way into the herd, and the herd bull would defend his cows and come after the intruder, often creating a shot for the hunter.

From a high vantage point, you can often lay out a long series of tones and pitches that simulate a mature bull seeking other elk. This is not necessarily a call for a fight or to take over the herd, but basically as a way to say “Hello, where are you?”
Elk are social animals and are very communicative while keeping in touch with one another. It is very common to get a response from a bull during early morning and late afternoons. Let your presence be known but don’t be overly aggressive with your calls.