Possible Clues:

• Until next time, in texts
• BFN alternative
• "Until next time," in texts
• 'So long,' in shorthand
• Texter's ta-ta
• Texter's 'bye now'
• 'Until next time,' in a text
• Texter's "Chat soon"
• "Chat soon," in texts
• Texter's toodle-oo