How much data can the “Response” field support?
The amount of data a response field can support depends on the Operating System. iOS (iPhone, iPad, iPod touch) devices can only support up to 478 characters. Android and Blackberry 6 / 7: devices can support upwards of 13400 characters.
Note: You can use the Webify option to add HTML or Web content to the Response field. Look here for more information on Webify.