Dane DeValcourt

20% of standard G.711 packet is used by IP, UDP and RTP headers.  G.711 payload consists of 160 bytes and IP, UDP and RTP headers total roughly 40 bytes.

QSIG is a peer-to-peer signaling system used in corporate voice networking.  Internationally, QSIG is known as Private Signaling System No. 1 (PSS1).  This open standard is based on the ITU-T Q.9XX series of recommendations for basic service and supplementary services.  Therefore, as well as providing inter-PBX communications, QSIG is compatible with public and private ISDN.

QSIG also has one important mechanism known as Generic Functional Procedures (QSIG GF).  This mechanism provides a standard method for transporting features transparently across a network.

Source:  Voice over IP Fundamentals (Second Edition) – Cisco Press

Wiki – QSIG

Light travels through a vacuum at a speed of 186,000 miles per second and electrons travel through copper or fiber at approximately 125,000 miles per second.  A fiber network stretching halfway around the world (13,000 miles) induces a one-way delay of about 70 ms.  Although this delay is almost imperceptible to the human ear, propagation delays in conjunction with handling delays can cause noticeable speech degradation.

Source:  Voice over IP Fundamentals (Second Edition) – Cisco Press

Wiki – Propagation Delay