To send a bulk SMS, you will need to have a list of phone numbers and a way to send the text message to those numbers all at once. There are several services and software options available that can help you with this, including:

1. SMS marketing platforms – these are web-based services that allow you to create and send bulk SMS campaigns to a list of phone numbers. Some popular options include Twilio, Sendinblue, and Plivo.

2. SMS gateway providers – these companies offer APIs that allow you to send SMS messages programmatically from your own software or application. Some popular options include Nexmo, Clickatell, and SMSGlobal.

3. Email-to-SMS services – some mobile carriers allow you to send an email to a specific address and have it delivered as an SMS message to a phone number. You can use this service to send bulk SMS messages by sending an email to multiple addresses.

To use any of these services, you will need to sign up for an account and purchase a certain amount of SMS credits to send the message. Then, you can use the platform’s tools to compose and send your message, and track the delivery and response rates.