From the Action Menu of the Lead you can click on the 'Communication' Icon to send an Email or SMS.

Directly from the icons in the top section of the Lead.  This will display in the red circle the number of communications already had with the customer and on click you will have the option of clicking the icons and selecting the required method of communication.

Expanding the Communications section of the lead you will see the history fo Emails, SMS messages and Phone Calls.

Additionally the Customer section of the lead allows phone calls to be made directly from here by simply clicking 'Call'. Note this is reliant on your PC or Device having phone call options available. 

Refer the Guide Automation - Email/SMS Failed To Send guide for setting up a workflow to notify Users that a SMS or Email Communication has failed to send.