Ghana code for all phones +233 ,often 00233 or 011233. Mobile phone system well advanced ,many providers ,all good.Ghanains already use phones to transfer money [ as phone credit ] and many have dual sim phones.

  Vodaphone has recently changed the landline codes. They are as follows:
Greater Accra: 030
Western:  031
Ashanti:  032
Central:  033
Eastern;  034
Brong Ahafo: 035
Volta:  036
Northern:  037
Upper East: 038
Upper West: 039

So, if the call is to a land line, the number would be like this (from the USA) 011 233 30 (Accra city code) xxx xxx.

If you are bringing your mobile phone from another country, be sure it is unlocked and can be used here.  Carry your travel charger and an extra battery if available.  Some phones from the USA will not work here, even if the SIM chip looks similar.  An inexpensive alternative would be to purchase a cell phone here (for as low as $35-40) which will give you a low end   phone . The main phone  market of many  in Accra is at 'Freddies corner' [ just above Circle] Latest iphone 4s 64's @ $1000 !! Here you can get your phone unlocked while you wait or buy one for your visit. It is not expensive and is an essential must have item.

Phones are pay as you go and  traders sell 2 or 3 types of strip from ghc 2 up everywhere.They will be pleased to load it for you as well.