The rush comes in the wake of CCK stressing that the deadline will not be extended.
The CCK is requiring all subscribers to give their full names, physical and postal addresses, dates of birth, and alternative means of contact when registering their numbers.
The mandatory SIM card registration launched by the government is expected to record the personal details of some 20 million subscribers by 30 July.
CCK Director General Charles Njoroge commented, the process which started last year within the industry, has so far netted between 50 to 60 per cent of subscribers.
Safaricom and Zain have already registered a significant proportion of their customer base, courtesy of their money transfer services, M-Pesa and Zap, which require customers to register before they can access the services.
Information and Communication Permanent Secretary Bitange Ndemo has instructed dealers around the country not to sell SIM cards to customers without registering their details.
Last year, President Mwai Kibaki directed mobile phone operators to register their customers to boost national security and reduce phone related crimes.
These include kidnappings where criminal gangs have in the past asked for ransom money to be paid through mobile money transfer services.
By BRIAN ADERO, Kenya
