You can send mass SMS texts to your contacts. This will only work if you have an SMS number set up within your profile and if you have enough SMS text message licenses.
To send mass SMS texts, go to CRM → View Contacts, and search for your contacts. For a guide on searching for contacts, see this.
Once you have selected your contacts, click Actions → Send SMS. If you did not select any contacts, the SMS will be sent to all contacts in the search result.
On the next page, you can compose a message to send to the contacts. In the editor, you can select details to automatically be inserted in the message, such as the first name.
When you have finished composing your message, click the green Check License button to make sure you have enough licenses to send this SMS to the group of contacts. Once you are ready, click the blue Send button.