What is the proper way to save phone or mobile numbers for contacts in IFS? Please advise how phone or mobile should be saved in the Person screen in IFS.  

Customer is looking for clarity on formats for: 

1. Preferred Mobile Number Format
2. Preferred Landline Number Format
3. Format for saving a Landline number with an extension in IFS. (Important)
4. Preferred Format for Saving International Phone Numbers

Their users encounter call failures (call doesn't go through) when attempting to initiate calls through the CRM Panel due to an incorrect format. 

Customer is in IFS  App 10 UPD19