If you turn off data traffic on your mobile phone or are in an area that does not have good data coverage, SMS will nearly always still get through. We also recommend to use SMS for the GSM anti-jamming feature as this will only be triggered if someone suspicious is using an illegal jammer nearby.
All subscriptions include 10 SMS per month. When they are over, you can buy another 10 SMS for 7 SEK. The reason SMS costs money is that each SMS means a cost even for us.