There is a Test Group available located in the Contacts screen that you can add to your Groups and send test messages to.
Use the Test Group to proof your messages, test auto responders, troubleshoot connection issues and confirm your text as the proper encoding.
Two of the phone numbers (678 & 320 area code numbers) in the Test Group are robots. Whatever message you send to the robot, it will send right back to you.
To test an auto responder, simply text your keyword trigger to the robots.
To confirm proper encoding, send your message to the robot numbers. If your message is 160 characters or less and is received back as 3 text messages, re-type the message (copy and paste is a common culprit to this issue) and also make sure to use 1 bit characters (pretty much any character found on the US keyboard).
2 bit characters will also change the encoding. Characters such as ñ, ü, ã, £, €, ¥, ¢ ® will change the encoding. One text's maximum character limit will now be 70 characters per text instead of 160 characters.