What level of encryption are you aiming for?
"Encrypting a cellphone" is a rather vague postulation. Is your goal to deny access to your phone without a password but have stronger protection than a simple pin code? Or do you want only a certain portion of your data encrypted, such as text messages? How secure do you want?
Remember that the act of hiding information is in itself often proof you have something to hide. The level of security you need will be based on the sensitivity of the information you're concealing. Hiding text messages and phone calls to your mistress from your wife? Or are you protecting state secrets?
Sometimes a good meatspace solution will bypass any digital protection you can use. For instance, if you want a secure phone to use infrequently, get a prepaid simcard compatible with your current phone and hide it in the battery compartment. Swap simcards when you need to make a private call or message, then swap back and you're golden. Nobody inspecting your phone will be the wiser unless they witness you making the swap or physically inspect inside the phone.
Remember
rubber-hose cryptanalysis will beat you with even the best password. It doesn't need to be physical coercion, just a few unavoidable questions from the right people about what you're hiding. In this case, using
deniable encryption will offer a measure of protection if you're put on the spot.
What phone are you running? Operating system? What do you want to protect and from whom?
If you want to make a call that can't be accessed by a government agency, you'll probably need to look to encrypted VOIP.
Teamspeak is listed as compatible with iOS and Android on Wikipedia and has no form of government backdoor access to information being transmitted. If you're looking to hide your web browsing logs, you'd better start with a good VPN service to tunnel your traffic through. Even if your phone doesn't have the sites listed on it, your ISP can still have them on record. Lifehacker did a good article on the
Five Best VPN Service Providers but do your homework first. Some will still give your access logs to the government if requested by law, eg. for tracing child pornography. Also remember that a VPN is basically a second ISP bill each month, so decide how much you're willing to pay for anonymity. Since you gotta pay them, look into Bitcoins as an anonymous payment currency so the money can't be traced back to you.
Hope I've given you some leads. If you can tell me more about exactly what you want secured I might be able to help more.