One phone with 2 sim card slots
Each sim can be turned on or off(or both left on)
When calling or texting it asks you to choose which sim
Careful though or you end up telling the wife/gf that you "Can only stay an hr"
(cheap ones 20 quid on ebay but a nightmare to text with etc.....get a touchscreen /smartphone one rather than a nokia style 1990,s brick)