All These Phone Numbers

So i've been gathering phone numbers, every time people add me to whatsapp groups, for birthdays, events, etc, and well by jotting them down at event signups. i've gotten almost 10,000 local german phone numbers together.

Is there a service or software to use to message all of them via Whatsapp or text message?

Sorry if there is a more appropriate forum for this, but i couldn't find one that seemed fitting.

You can find an sms marketing company that supports the country to what that phone numbers belong.

After your found one, you can then send bulk messages to all of your phone numbers.