Hi Philhuk,
Thanks for your post and welcome to our community.
Very sorry that you're having trouble calling landlines from your mobile, this isn't good.
Is it a Virgin Mobile trying to call a Virgin Media landline?
Are all mobiles having issues with the same landline numbers?
Is it a business landline number, so maybe a premium rate number or just a standard landline number?
Do all numbers have enough credit or allowances to ring out?
Can you call other numbers, so are other mobiles fine to call on Virgin as well as other networks?
Let us know and we can take it further.
Emma_C - Forum Team