Come on, we're not talking about extreme sports hiking, and

you can consider yourself in safe domain if you:

1. go out in good weather only;
2. go with people who are at least of equal experience and physical conditions as you are if not more experienced and in better shape;
3. stay on established, well marked trail only;
4. always let your family/friends know where you are going before you leave.

Those telecom gears you mentioned are of limited help because:

1. GPS must have pre-loaded trail information and not all such information is accurate if you venture away from well-established and well marked trails;
2. Mountain trails are normally outside the coverage of cell phone networks;
3. Walkie-talkies are heavy and run out of battery very fast.

Just because you have such gears doesn't mean you are a lot safer than those who don't. It's better to rely on common sense, which is listed out above.