How many times you have mis-placed your smart-phone and you try to call the number and hear the sound coming from to retrieve it. What if the smart-phone is set to silent mode or low volume at the point you mis-place?
For users who are into support line, missed calls from clients are norm due to many calls coming in. However once you get back to them or they finally get through to you, all past missed calls are redundant
For those who are not on un-limited voice plan from your country mobile network operators, you are usually given only certain minutes of free calls before they start to bill you for the extra minutes every month
Are you in insurance, property or other agent line of work? Very often when prospective customer call you on your smart-phone, you want to see the most recent call entries from that customer before you answer the call
Some users are given company issued phones. The phone bills are paid for by company too. However some companies would like to ensure that calls received and dial-ed out are strictly for business purposes