16. A method for wireless communications, said method comprising: receiving text that has been entered by a user of a mobile communications device wherein said text is received when said mobile communications device has been set to a first mode in which said mobile communications device accepts text input instead of speech input, wherein said text is received during a call in which a second communications device is configured to receive speech packets, and wherein said mobile communications device is settable to a second mode in which said mobile communications device accepts speech input instead of text input; converting the received text to a synthesized speech signal; encoding the synthesized speech signal to produce a plurality of corresponding speech packets; transmitting the plurality of corresponding speech packets over a wireless communications link to said second communications device; and transmitting an audio notification informing said second communications device that speech from said mobile communications device following said audio notification will be converted from text, wherein said audio notification is transmitted prior to transmitting said plurality of corresponding speech packets, and wherein said converting the received text to the synthesized speech signal includes using stored characteristics of the user's voice to produce the synthesized speech signal.
16. A method for wireless communications, said method comprising: receiving text that has been entered by a user of a mobile communications device wherein said text is received when said mobile communications device has been set to a first mode in which said mobile communications device accepts text input instead of speech input, wherein said text is received during a call in which a second communications device is configured to receive speech packets, and wherein said mobile communications device is settable to a second mode in which said mobile communications device accepts speech input instead of text input; converting the received text to a synthesized speech signal; encoding the synthesized speech signal to produce a plurality of corresponding speech packets; transmitting the plurality of corresponding speech packets over a wireless communications link to said second communications device; and transmitting an audio notification informing said second communications device that speech from said mobile communications device following said audio notification will be converted from text, wherein said audio notification is transmitted prior to transmitting said plurality of corresponding speech packets, and wherein said converting the received text to the synthesized speech signal includes using stored characteristics of the user's voice to produce the synthesized speech signal. 17. The method according to claim 16 , wherein said method includes, in said second mode, receiving a speech signal from a microphone, and producing encoded speech packets based on said received speech signal, and wherein said method includes, in said first mode, converting said received text to said synthesized speech signal, and encoding said synthesized speech signal to produce said plurality of corresponding speech packets, without performing echo cancellation on said synthesized speech signal.