There are no known viruses using the SMS (Short Message System) under GSM cellular phones. However, several techniques of crashing a phone by sending a malformed SMS text message to it have been found over the years.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
None of the known methods of crashing a phone like this this work universally: they typically only affect a single GSM handset software version from one GSM vendor. As there are hundreds of different GSM handsets from several vendors with the built-in software frequently updated, it would be impossible to come up with a technique that could affect more than just a handful of existing phone models.
Thus, a risk of generic 'SMS Killer' is minimal.
Known techniques of crashing GSM handsets via SMS messages include sending a message with 160 '.' or '-' characters in a row to a recipient with an old-style GSM handset, or by sending SMS messages with a malformed User Data Header, as outlined by ITSX researcher Job de Haas.