Many IFTTT recipes have the option to send IFTTT a SMS with something tagged but how do I send the message to IFTTT? To which number the message has to be sent?
Jan is correct. Sign into IFTTT, activate the SMS channel by proving your number is your own, then you'll be given a custom number to use with IFTTT. Add that to your phone and you should be good to go!
I have activated SMS channel 1 month ago because I have one recipe activated that sends me daily forecast SMS but at the time of activating SMS channel I didn't got any custom number.
You probably just didn't note your number. Sign into IFTTT and head to the SMS channel. You'll see a screen very similar to what Jan has posted above. That number is your custom IFTTT usage number.
You have to join the SMS channel to get an "IFTTT phone number"
I have already done that but I didn't got any "IFTTT phone number".
If you already signed up the link above should show you your phone number you used to activate and it AND your IFTTT phone number.
If it does not then try deactivate and reactivating it.
Thanks. I didn't knew that!