However, this does not always mean that a service provider comply on all mobile- and tele-services.
To send a text message (SMS)
on Sweden Comviq Mobile - Tele2 (COMVIQ)
£0.15 ($0.23)
on Sweden Telia-m Mobile - Telia Mobile
£0.15 ($0.23)
on Sweden Vodafone Mobile - Telenor (Vodafone)
£0.15 ($0.23)
SMS utilizes the networks signalling capacity (MobileApplicationPart signaling), which lacks of charging abilities.
Operators which exchange signaling usually clearing their accounts (pay each other), both with national and international signaling.
BThe CallDataRecords (CRD) from SMS are made in the SMS-Center, not by the signalling data.
If e.g. a UK-service provider sign a roaming agreement with operators in Sweden, their SIM-cards are allowed to "log on" (location update) the Swedish network.
Sending an mobile originated SMS will then load the signaling links from Sweden to UK, where it's SMSC is located, but the Swedish operator will not make any money, only have additional expenses due to increased signaling load.
That is why many operators have blocked their SMS signaling unless the operators/service provider have signed a special SMS-agreement.
So for your case, I think you have to ask GeoSIM customer care, if they (still) support roaming in Sweden (MobileOriginated-SMS and MobileTerminated-SMS).