on 31-05-2018 20:57
That is the generic text number for an SMS being converted to an MMS.
Also, if using an iPhone, don't add a subject line to your messages and turn of that and MMS in settings.
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone7 (EE)
on 01-06-2018 12:10