A message can be repeated, but not in that short time of a few seconds.
Pagers may ignore messages if they are received again. The user may
repeat the message, but not the transceiver.
To allow all 128 ASCII characters, a null-terminated string cannot be
used. Instead a length is used to define string length, to allow
null-character in that the message string.
The print function in frame.c is improved and used to present the
string.
Jitter buffer is now based on packets, not on samples. The frames are
dejittered in received form. After reading from jitter buffer, they are
decoded in correct order. If a frame is missing, it is concealed by
repeating audio.
Features are:
* Packet based buffer
* Random in, first out
* Adaptive delay compensation (voice)
* Fixed delay (data, optionally MODEM/FAX)
* Interpolation of missing frames
* Any sample size
