In this modern era of cellphones, text messaging services give spammers and telemarketers even more ways to annoy you than a home phone. Since your cellphone is usually on hand at all times, an unwanted text bugs you no matter where you are.
Fortunately, there are ways to filter message notifications from unknown contacts and even block spam message sender numbers outright.
Here are the steps for stopping those annoying cellphone junk text messages for good.
Block the spam sender's number
The first step is to block the sender of the spam text message.
On an iPhone, tap the "i" icon in the upper-right corner of the text message, then on the next screen, tap the displayed sender number. This opens up a bunch of options but for this purpose select "Block this Caller."
Optionally, you can also turn off notifications for iMessages from senders that are not on your contact list. To do this, go to Settings >> Messages >> toggle Filter Unknown Senders to on (green indicator on).
Keep in mind that even though texts from a particular number won't be delivered when you block it on an iPhone, they can still leave a voicemail (but you won't get a notification). Also, the blocked sender won't receive a notification that the text message was blocked.
On Android, while on the text message, tap the three vertical dots in the top-right corner of the screen to access the menu. Select "People & Options" then Block.