"£1 FREE credit so you can get started straight away

Great rates from just 1p per minute

No connection fee* (calls made via App only)

Easy to use - just tap the app whenever you want to make an international call

Contacts appear in the app so you can dial straight away – no need to manually enter the number you are calling

Check your balance and destination rates

Access number is free for Tesco Mobile customers"

http://phone-shop.tesco.com/international-calling-cards/tesco-international-calling-card-app.aspx?icid=icc_sec-module_icc-app

You can call UK Numbers as well as intl ones from the app. 4p connection. I wonder if you could use it from Tesco Mobile Payg Phone to get your landline calls down to 4p connection 2p a minute. Given that the access number is free from Tesco Mobiles.