  Present day, the internet telephony growth is much faster than previous. Now
we are familiar with digitized packet of voice stream. So, we have required
VOIP communication. SIP is one type of VOIP protocol. This one has a SIP proxy.
There have one of the important communication environment Wireless LAN (WLAN).
WLAN have different radio link standard. Here I am comparing SIP protocol in
two radio link standard 802.11a and 802.11b environment. The first one have
maximum transmission rate of 54Mbps and second one have maximum transmission
rate of 11Mbps. In this paper I want to show the results in a comparative plot.
These comparisons include server /client throughput, packet drops, end to end
delay etc.
