Zoiper is a program for making calls over the Internet. It is a cross-platform app, which makes it a good softphone to be used on different devices.
ZoiPer has free and premium versions (costs 9.99 USD/year or 0.99 USD/month).
Disadvantages of the free version:
no possibility to transfer calls between employees
the app doesn't have push notifications, so you need to make sure it's turned on to receive calls properly.
However, if you purchase the premium features (subscribe for Push-notifications), the app will have push notifications and you will receive calls even if the app is closed.
The app has a 7-day trial period for premium features.
Before installing the app — go and create the SIP account for your agent.
Once you install the application on your computer, configure your Zoiper software settings in a few steps.
When you start ZoiPer for iOS for the very first time, it should automatically take you to the "Account" screen. If this is your first SIP account, you should see a setup wizard that looks something like the first image below.
Click "Add Account +" (if necessary).
Answer to the question "Do you already have an account?" => "Yes".
Choose "Manual Configuration".
Then choose an account Type "SIP Account".
Get the user information you gained in the main SIP-accounts settings article and put it into the corresponding fields.
In the "Additional Settings" section, select "Audio Codecs" and choose GSM, a-law, and u-law.
The device should display "Registration Status: OK".
Your device is now registered.
If you want to subscribe to push notifications and receive calls even if the app is turned off, you should go to Premium features section and click on Subscribe.
After that you should choose the needed subscription period and click on Sync Products.
Once you set the configurations — make a test outbound call to check the connection.
NB! For push notifications to work properly, several conditions should be met:
Latest IOS version
Push notifications in the phone settings should be allowed
Go to iOS Settings > Notifications > Zoiper and turn on Allow Notifications option.
3. Incoming calls settings in Zoiper app should be configured appropriately.
Go to Settings - Incoming calls and allow push notifications there.
Keep in mind that if you restart your phone, you will need to launch Zoiper manually for push notifications to work.