When Would I Need RTP Header Compression?
RTP header compression can be useful on any narrowband link. Narrowband is
usually defined by speeds less than T1, but in making your decision whether to
use CRTP, you should consider not only your link speed, but also the available
router resources (CPU) and your overall traffic patterns. Since CRTP is performed
at the main processor, enabling it could cause your utilization to jump if
you have high packet rates (lots of headers), many serial interfaces, or large serial
interfaces.