Hi! Variable like that are "static". You can use theses variables in other biding. If you need to bind phone's variables, it is better to call Ressources and bind phone's variables.
Ex. : you need to have a phone number like that : + 33 09 56 74 56 67 but you receive data like that :
- static variable (frenchCode) : +33
- add Collection with some phone number
In expression editor you coul have something like that :
${frenchCode} ${Phone number frome collection}
Hope I'm clear...