Here is an example using the Talkie library to transmit encoded speech with the HamShield. The end result sounds a bit robotic, but pretty readable. You must download the talkie library, located here: https://github.com/going-digital/Talkie
I have included many pre-encoded words, just uncomment the words you would like to use in your sketch, then use the voice.say(spXYZ) function.
Here is the sketch: