How to find a Sri Lanka person's phone number is searched through the internet. Normally USA, Canada, Australia and other developed countries, there are free and paid facilities to find a person's contact details. This service is provided regardless of which kind of land line or mobile phone they are using. Website based programs assist people to find out the required numbers within minutes, if you provide the person's correct information. But in Sri Lanka there is no such paid services are not available. Only the SLT directory service is available and it is too free to search through. Reverse phone number checking facility is not available in Sri Lanka for the public.
To find a person's land line number in Sri Lanka, Business contact, any Government position or working in any private organizations can be searched through the Sri Lanka telephone directory, if they have SLT phone numbers. There are three major Sri Lankan phone service provider's telephone directories available in printed book format. Also these phone directories are available online too.
SLT Business Directory
There are no mobile phone users' directories available in Sri Lanka.
So there is no way to find it.
If you know the person's name you can check for his profile in the websites.
If he had registered his mobile phone number in any of the websites like Facebook, Google+ or any other social network websites, you can find it from there.
It is illegal for a company to provide a person's personal mobile phone number to others in Sri Lanka.
Like wise a common man is not allowed to hide his mobile phone number when he is making a call. It is an offense according to the Sri Lanka Law.
Many latest Cell phones have this hide the caller ID facility, but your carrier in Sri Lanka won't support it.