Unfortunately, phone carriers are becoming stricter with the content sent via text message. Similar to email, some cell phone carriers have implemented filter systems to block spam and other unwanted messages.
The Don'ts:
Don't add additional links
Don't use hashtags or @ (# or @) most spam messages contain email addresses or website links.
The Do's:
Change your text message content per event. Keeping the same message for all your events will raise a red flag with the phone carriers.