You are able to send a Webform link in an SMS as part of a Job Type Communication as well as a one-off SMS. 

To send the Webform Link in a Job Type Communication in your Web Portal > Jobs > Job Type Templates > Select the Job Type Template > Select SMS as the communication > Add the Webform Link using the placeholder to the content of the SMS > Save. Ensure that the Webform you are wanting to send is added as a Webform in the Job Details of the Job Type Template. 

To send a Webform link as a one-off communication in your Web Portal > Select the Quick Send Icon form the Top menu bar > Select SMS > Paste the Webform link from the Form