most people have insurance, so they do not care if their phone breaks, the best way is usually through home insurance which covers you for up to £1K in goods which you carry on you, so that your laptop, tablet and phone, etc are all covered.
another way is insurance through your bank. this is because insurance with your phone company is usually a lot more expensive and a lot more trouble in dealing with claims, etc.
well if there is an app out there that can do it, then i am sure google will help you find it.
otherwise you could forward all your calls to your other mobile,very easily using the settings function but then that would mean you need to pay for all those calls as well as pay for 2 different mobile contracts or sims.
what is the point in having a phone if you are too scared to use it? i suggest you get insurance, surely the cost of forwarding calls and texts will be more than insurance, plus with insurance your phone is covered, therefore what happens if you smash or drop your phone when your not out jogging? or it gets stolen?