Add new features to the apps on iOS and Android

We have 3 native apps - Taxi aggregator - 1 for passengers / 1 for drivers - on iOS + 1 app for drivers on Android If you are ready for the work, please, let me know how much time can take EACH point (not fully, but please describe appox. time for every point) List of planned functional improvements: 1) To implement a new feature “to make a call via Taxi app” so the driver will be able to call to passenger and and vice versa (2 android apps/1 ios app) Task: passenger and driver have to have an opportunity to call to each other via app using Internet connection (not mobile network) 2) To add a button for the previous n.1 feature (2 android apps/1 ios app) Task: You just need to add a button on the screen for the feature n.1 3) To add a countdown indicator of time and kilometers prior to arrival at the destination point (1 android app) (check the screenshot) What we have now: the line counting minutes and kilometers to the destination in the upper part of the screen. What you need to do: to move this line to the bottom of the screen, add a countdown indicator where the color band decreases with time. 4)To add sound signals to some push-notifications (1 android app) Task: When a passenger makes a taxi-request, the driver receives the new trip/ postponed trip notifications. On these notifications it will be necessary to set a certain sound signal. Please, let me know how much time can take EACH point (not fully, but please describe appox. time for every point)