In an area enclosed by an eruv, emergency medical professionals and volunteers who always carry beepers or cell phones may carry these devices on Shabbat. Similarly, one who always carries a pistol or rifle may carry it on Shabbat. Muktzeh is not an issue, because many maintain that a pistol is a kli she-melakhto le-heter, since its purpose is defense and deterrence. Similarly, since a two-way radio is designed to help save lives, it is also a kli she-melakhto le-heter. A cell phone is used primarily for calls that are unrelated to saving lives, so it is a kli she-melakhto le-isur. Nevertheless, one may carry such an object to use it le-tzorekh gufo, and therefore it may be carried to save lives.
However, in an area without an eruv, one should not carry these items. When there are life-saving reasons for people to remain close to weapons and communication devices in case of emergency, they may carry these items to places where one normally goes on Shabbat, such as to prayers and celebrations. If we do not allow this, no one will volunteer to undertake security and rescue efforts. In general, this consideration is used to permit rabbinic transgressions. Only under very pressing circumstances is it permitted for one to transgress Torah prohibitions (see above, n. 12). Therefore, one should carry the two-way radio with a shinui (for example, under one’s shirt), which makes the transgression rabbinic. However, one should carry the gun normally, because it would be dangerous to carry it with a shinui. Additionally, some maintain that for security personnel, a weapon is not considered something that is carried, but an article of clothing that is worn.
However, one may not carry a gun or a two-way radio on Shabbat for the sake of a leisurely stroll to a place with no eruv. Thus, one should not take a walk outside the eruv in an area where he must be armed for security reasons, as this will require people to carry weapons needlessly.
If a soldier wants to leave his base in order to participate in prayer services taking place in a nearby community, and he will need to pass through an area with no eruv to get there, after he leaves the base he should rest his gun and two-way radio on a mekom petur. He should then carry the items from there to the community. He should do this on his way back as well, as explained above in 21:7.
Regarding putting out a dangerous fire, see 16:6-7 above. Regarding alarm systems, see 17:15 above.