I too got this error but only after upgrading from 4.4.0.68 to 4.4.0.72. Prior to this I had no issues sending sms while having voLTE enabled. Calling and receiving smses does still work.
I’m also using the same device with Danish language. My provider is HALLO (TDC). What’s your provider @elkiaer ?
Just checked changing language from Danish to English (UK) does not help (which would also be a stange fix).