You can download the iOS App in the Apple App Store when you search for "YodelTalk". Alternatively, use this link to access the app or go to yodel.io/apps. You can use the iOS App with or without the Slack integration.
After downloading the iOS App, you need to log in with your user credentials from Yodel:
After logging in you will see the home screen which lets you call any number. Please be sure that you use the international call format for making calls (e.g. +1 for the US).
You can select from which Yodel number you want to make a call from if you have several ones in your account.
Once you're in a call, you have the options to mute the call, use the dialpad and select the input and output for the audio.
By default your iPhone will ring when someone calls your Yodel number. You can deactivate this in the "settings" menu.
An incoming call is shown on your screen and by clicking on "answer" you start the call in the app.
Pro tip: To call a contact, go to your native phone app and click on the person you want to call. You need to press and hold the phone icon in the contact's details and then you get the option to make the call with the Yodel app.
Side note: The iOS app will only ring when you are logged in your Yodel account. Currently, we don't support the app for several Yodel accounts. You need to log out and log in to your other account to access the respective call.