NAT question

This is my scenario.

I have a default route 0.0.0.0/0 pointing to my backhaul provider.
I also have my own /20 IP assignment.
I have clients who do not have public addresses are are Natted at our edge router.
These clients when they do a IP Whois test are showing up as the IP of my provider.
I want these clients to be natted but to use an IP from our own assignment and not my providers so when they do an IP Whois lookup, it will show our own IP address.
Is this possible and how.

Thanks

Paul

Did you exempt them from the masquerade rule?

Normally it should show your own IP, unless it is not a public one. First check if your IP is public.

all IP’s are static

A static IP does not mean it is public as well. Check the simple table below which gives a general idea
on what are private IP and what public.
http://en.wikipedia.org/wiki/IP_address#IPv4_private_addresses

hi,

The Ip range are fully routed public addresses

Sorry, but may be I read it wrongly at first your question. You mean that you want to assign of the IP that the ISP has given you, to the devices of your LAN?
If that is the case you should do netmap.
http://wiki.mikrotik.com/wiki/Manual:IP/Firewall/NAT#1:1_mapping