VoIP Phones - zoiper

Back up to the VoIP Configuring page
From AAISP Support Site

You can download a part-configured Zoipier from here: Configuration instructions for Android and iOS

You can purchase Zoiper here: https://www.zoiper.com/en/shop/buy/zoiper5

Zoiper 3.46.1 example on an iPhone.

    1. Download App and go to Settings -> Accounts & select 'Yes'
    2. Click 'Select a provider'
    3. Select 'AAISP'
    4. Enter your VoIP number (+44...) and SIP password then click 'Register'