If you are porting to Visible you need to leave your old service active until you get the new phone and have ported in, once you finish the port in process and you have service cancel your old carrier you can toss the card.
If you are a current Visible customer you will need the card for the new phone unless you were sent a new card with the new phone. Once the new card arrives and is activated in the new phone then toss the old card and send the trade in phone back to Visible.
This information is based on what I have read. I didn't port in to Visible but have transferred a SIM card from an old phone to a newer phone without issue. I recently moved from the old unlimited new plan, I was sent a new card and once I activated the old card is dead and serves no purpose to keep unless you want to make a necklace or something out of it.😊
Looking for forum topic about new plan switching like you, so new SIM card preparation. Concern for preserving text history, contacts, apps. General internet describes settings on Google to backup. Noticed settings for contacts have Google settings, but have not found text storage.( MMS versus SMS soup to me too.) When I got a new phone it was tedious loading apps,wallpaper, details. Same phone may ONLY be about text messages in SIM domain?