The issue is with the safari browser blocking the ability of the pop-up window to select send a SMS option.  

To resolve this use Google Chrome Browser - to download this to your iPad desktop follow the instructions contained in the link below:

When you click on a mobile number (not the mobile symbol) as shown below: 

 A pop up will appear as shown below:

Select the Send SMS option: 

Type your text message into the SMS window as shown above.  Click on Send to send. 

To see a video guide on sending out as SMS please click here.