This adds a one-click install for both the Desktop and Mobile Zoiper APPs in the User Portal. The page is accessible by end users.

I used the FREE Zoiper OEM account

Go to: https://oem.zoiper.com/
Sign up for Login
Configure your Desktop and Mobile Apps with the information you want.
Then click "View" Under Mobile. 
Under the heading "The easy way: send your customers to our landing page" there is a LINK with a PAGE ID:
https://www.zoiper.com/en/page/MYPAGEID?u=&h=&p=&o=&t=&x=&a=&tr="
Copy the page ID

Below the title " The Do It Yourself way: make your own page with instructions" there will be a LINK with a MOBILE PAGE ID:
https://www.zoiper.com/en/page/MYMOBILEPAGEID?u=&h=&p=&o=&t=&x=&a=&tr="
Copy the mobile page ID

On your server
git clone https://github.com/fusionpbx/fusionpbx-apps
Copy or move the directory 'zoiper' into your main FusionPBX directory
cp -R fusionpbx-apps/zoiper /var/www/fusionpbx/app
chown -R www-data:www-data /var/www/fusionpbx/app/zoiper

Log into the FusionPBX webpage
Advanced -> Upgrade
Menu Defaults and Permission Defaults.
Log out and back in

Advanced -> Default Settings
Add a Default Setting

Category: zoiper
Subcategory: page_id
Type: text
Value: MYPAGEID
Enabled: True
Save

Category: zoiper
Subcategory: provider_id
Type: text
Value: MYMOBILEPAGEID
Enabled: True
Save

Category: zoiper
Subcategory: outbound_proxy
Type: text
Value: OUTBOUND PROXY SETTING
Enabled: True
Save

Then go to Apps -> Zoiper
Superadmin will see a list of ALL USER EXTENSIONS
Users will only see the extensions assigned to them.

Click on a link and it will take you to the Zoiper Site. Follow instructions there to download and install.