Random text string in messages

Wild guess: It's an encoded message from a terrorism organization telling about a scheduled event :)

Serious Analysis: Call your carrier support for more information. This looks like some internal information (metadata) that accidentally leaked out. I made this guess because that message

1. Uses colon for field separator (very common in Unix systems)


2. Contains a time stamp (1496949959776 is 19:25:59.776, Jun 8, 2017 UTC)


3. Contains a Base64-encoded data, which gives a 20-byte nonsense after decoding


4. Contains an unused number from Seville, Ohio


5. Contains a 32-character code in an unknown format

If you don't want to dig too deep or you're not so curious, then you can safely ignore it.