Skype credits alternative

Now that Skype have discontinued credits, I'm stuck for which service to use instead. Their plan to move to country-specific subscriptions is bonkers in my view - a lot of people rely on the ability to call anywhere, rather than having to sign up to subscription that fits what they need that day.

I travel a lot for work, and used to use Skype for sporadic international calls to a range of places. Does anyone know something that could replace this service? I've seen other almost similar discussions but I wanted to clarify:

- I'm looking for something that would allow me to contact people who don't have a specific app, or even landlines. Being able to call my bank while overseas, for example, would be useful, and I'm not going to get them on a WhatsApp call.

- I don't want to set up a subscription or be locked into a plan (my requirement for calls come and go)

- Ideally, like Skype, I could load up a bunch of credit and use it on whatever

Recommendations would be gratefully received.