The fact is that Smart, Globe, and others in Phil, have the bad habit of sending unsolicited text and the cheek to charge for them....
The larger the load, the more often the texts are received and charged for...
To avoid this robbing behaviour, to a certain extent, keep the re-loads down to 100/50 or 30 PHP.
When I was there the first time I used to get all sorts of welcoming texts, and while checking my online T-mobile account, I noticed several charges for the received texts.