Almost any mobile phone is capable of generating DTMF, providing a connection has already been established. This is for the use of phone banking; voicemail services and other DTMF controlled applications. If your mobile phone can not generate DTMF (or your home or office telephone uses Decadic Dialling (Pulse Dialling) you can use a standalone Tone Dialler or White Box, which you may or may not be able to find on the market.
DTMF was designed so that it is possible to use acoustic transfer. The DTMF tones can be sent from a standard speaker and be received using a standard microphone (providing it is connected to a decoding circuit of some type).
There is an application used with microcontroller which displays received DTMF tone on seven segment display.