SIM Card

Don't know much about Danish SIMs but I have always found this blog helpful (a page per country):

http://prepaid-data-sim-card.wikia.com/wiki/Denmark

It seems that some Danish mobile providers may not allow international roaming on their SIMs or have restrictions, so don't count on using it after you leave Denmark. Just check at a mobile store, perhaps, to see if that particular SIM allows EU roaming.

I've had good luck with my Dutch Vodafone SIM, which I bought on eBay, for roaming within the EU. I've never actually used it in the Netherlands, nor have I used it in Norway, Germany, or Denmark, but I assume it would work just fine there:

https://www.vodafone.nl/_assets/downloads/tarieven/tarievenoverzicht_prepaid_buitenland_1_juni_2017.pdf

Vodafone currently gives you 2X data through the summer (maybe it will continue) so you can get 2GB for 10 euros for a month, instead of just 1GB or 6GB instead of 3GB for 20 euros for one month. The downside of this SIM is that it doesn't allow cheap calls to EU numbers - they cost 20 cents/minute unless you are calling Dutch numbers. Incoming calls and texts are free, though.

You can still buy this SIM from eBay (search for "vodafone you sim") from seller "cheapeusims." Look for my write-up from last year on the technology board here.

Last summer when we were in Denmark I thought about getting a local SIM, hoping that it would also be usable in Sweden and Norway later in our trip. The latest RS advice on phone SIM cards that I'd seen at that time was to go to a cell network provider store and get a SIM card, expecting that with the new EU roaming rules the card would work pretty much everywhere. In Copenhagen, we stopped touring long enough to give this a try for an iPhone. We went into both a Telia and a Telenor store (2 of the big cell providers in Scandinavia). We got the same response in both. They could not help us since we were not Danish citizens. (Something to do with terrorism worries I assumed.) They recommended going to a 7-11 store and getting a reloadable SIM card. We went down the block to a 7-11 and yes the clerks said they could sell us a local SIM card. I believe the price was either 40 or 50 DKK that included 10 DKK worth of cell time. They said we could add more time at any 7-11. However, they were unclear about the EU roaming situation and were very unsure that we could find another store in Sweden or Norway to load more time on the Danish SIM card. That being the case, I decided not to buy the SIM card and we managed the entire trip by using WiFi and printed information only. If I were you I'd try to ascertain that you can load more time on a Danish SIM if you are not in Denmark. Or guess how much you might need after leaving Denmark and put that amount on the card before you got on to other countries.