Its a little complicated due to different carries. Most texting is passed on from the cellular side and when traveling, most people will turn off roaming, cutting off the cell connection. If, lets say someone has T-Mobile that includes international travel, they will still receive texting. If someone or most carriers when at sea for day after day will lose connection and get no texting. Forcing or replying to a text will connect to the ships cell connection or connect to the closest land base, causing a roaming fee. It is possible while at sea to trick the phone by temporally turning off airplane mode and turning on WIFI calling. this will usually make the phone think it is in connection to a cell tower and download all your texts and you can send texts during that time also. Of course an app like whatsapp will always work because it relays on WIFI only but the other person must have whatsapp also.