How to Monetize Multiple Spain SIM Cards for Maximum Profit?

Hi awesome people,
I recently acquired several Spain SIM cards, and I’m currently using them for phone-related activities. However, I’m looking for effective ways to generate revenue from them.

Here are a few ideas I’ve considered:

• Bulk SMS or marketing campaigns.
• Selling verification services for online accounts.
• Using them in phone farming setups for passive income.

Are there any other proven methods to monetize these SIM cards? For example:

• Can they be used for affiliate marketing or lead generation?
• What platforms or tools should I explore to optimize earnings?

I’d love to hear your suggestions or experiences in leveraging SIM cards for profit. Any guidance would be much appreciated!

How many do you have, because if you only have a couple it's not worth setting up any systems