Unlimited Mass SMS App?

[#1]

Can anybody recommend an app that lets you send out a text/SMS to your entire contact list? Not all of my contacts use what's app. So it must be some other SMS sending app. There seem to be a few out there, but I'm not sure which one is best. It needs to be unlimited texts. My contact list is 21,040 !!!  Grown over the years. Mainly UK & London based contacts but also several people from around the world. Due to all the events and shoes I've done and of course the countless networking events I was part of. And there were several people who subscribed to my newsletter.  I am going to update & clean up the database. Which app should I download? I'd like to try it first before paying a subscription. My Huawei P20 phone SMS only lets me send 1000 texts a time, and that too, by creating a label/group. 

[#2]

Hi @emmanuelray be aware that giffgaff does not allow the sending of automated/group texts. If you try you will find that your services will be blocked and you will then need to contact an agent to unblock them.

[#3]

Thanks. I had no idea. Although I think the block is ridiculous. But if I use an APP it should be different, right? I have asked a few people I know and even posted on Facebook, plus did some research. Not arrived at the right thing yet. I think the only option I have is to give the free SMS Apps available on Google Playstore a try and pick one that works.

[#4]

Text bombs giffgaff will bar your service they only allow one text at a time @emmanuelray

[#5]

Giffgaff bars you for lot's of texts at one go.