Transmission rate

Host A digitizes real time speech by sampling at a rate of 8 Khz, and converting each sample on-the-fly to a 8 bit representation. As soon as 48 bytes of digitized speech have been collected, A immediately adds a 5 byte header to form a packet and starts transmitting the packet at a rate of 128Kbps to Host B. (At the same time it is collecting more speech bits to form the next packet.)  Assume a total propagation delay of 4 msec, between A and B. As soon as Host B gets a complet packet , it is able to reconstruct and start playing out the analog speech waveform.
a. How long does host A take to collect 48 bytes of digitized speech?
b. What is the delay between speech at the input of Host A and its reconstructed  version appearing at the output of Host B?
c. Would this scheme work if the transmission rate between A and B was 64Kbps?