To text a lot of people at once, you need to have an app that allows you to do group texting or mass texting. Examples would be Signal, WhatsApp, or Ringover.Once you have an app that allows bulk messaging or mass texting:
Compose your message.
Choose the contacts from your contact list and click the send button.
You can also type or paste the number in international or local format..
International format example: +447520633003 or 00447520633003 if the recipient is in the UK.
Local format example: 256 584 2044 if the recipient is in the USA.