Nigeria’s country code is 234.
When dialing from Nigeria, dial +9 (followed by the) International Code (followed by the) phone digit digits.
Callers dial +234 (followed by the) phone digit digits when dialing into Nigeria. In Nigeria, there is also a business named Elixir Communication Worldwide that sells mobile phones to the blind and visually impaired. All mobile carriers have roaming agreements with other mobile providers worldwide.