Is it possible to hack a cell phone?

[SubliminalX7]

Yeah, there are plenty of backdoors out there

 

[Goblin1986]

You can put hacking software on phones such as blackberrys which gives the attacker full access to the phone at any time without any sign of activity, however you can do a factory reset which wipes the hidden software... so I always do a factory reset on certain phones which can be hacked if I purchase them.

Can I put hacking software only on blackberry or samsung as well? I do not know how to do a factory reset!( Is it difficult to do it?

 

[carnageX]

Can I put hacking software only on blackberry or samsung as well? I do not know how to do a factory reset!( Is it difficult to do it?

Factory resets are done in through the menus.

In Android is under one of the following:
Settings -> Security
Settings -> Storage
Settings -> Backup & reset