FAQ - What number should I use when sending SMS message to this site?
First you should try to type in the number as shown on the page. Including the plus sign. This number is an international number and includes the country calling code.
Some phone companies requires you to enter an international call prefix. This is a number that tells the phone system that you are calling out of the country. But it should not be required when sending SMS text messages, but some phone companies require it. In that case you enter the international call prefix then the number listed on the webpage. You should then probably skip the plus sign.