From Worldwide Mobile Guide
North Korea has not fully adopted mainstream internet technology because of its isolationist policy. According to some Internet resources there is only cellular operator in North Korea - Koryolink (owned by OTH (75%) and Korea Post & Telecommunications Trading Corporation (KPTC) (25%)). But, unfortunately, it has no website to check its tariff plans and services.
Until November 2011, no mobile phones can dial into or out of the country, and there is also no Internet connection.
They say handsets cost around 50 euros or 64.44$ and as for basic monthly subscription it costs 900 KPW, which is about 6.64$ at the official exchange rate and less than half of that at street exchange rate. It is unclear what is available for that basic charge.