Making phone calls in Papua New Guinea

Getting access to landlines can be difficult depending on your building, however mobile coverage is quite good in PNG in all major towns/cities.

There are 3 main carriers, Digicel, Vodafone BMobile and Citifone.

Digicel is the largest carrier, but that doesnt necessarily make it the most reliable. They have the most coverage however.

Vodafone BMobile is getting to be a quite large carrier, their coverage is continually growing and they are present in most large towns in PNG without issue.

Citifone is part of Telekom (Government). Their coverage isn't as good as the other two to my knowledge.

There are different plans you can subscribe to, most people use prepay as post paid can be more expensive, prepaid topcards are available in most outlets for both Digicel and BMobile. Amounts vary from K1 to K100. With this you can buy call or SMS packs that give you X amount for Kx. These are generally good value, and you can purchase international calling packs also.

You can also redeem your credit for data packs, these vary, but expect to pay around K70-80 for 1.5GB of data.

Personally - I recommend BMobile, although slightly more expensive at first glance, the way their billing works behind the scenes, means I actually get more value for my money. Their service is also more reliable and support is fantastic when needed.

Getting a landline in PNG is a challenge.  Step one is to go to the local Telikom office and ask them to install a line.  Telikom is a State Owned Enterprise and the SOEs in PNG are notoroiously inefficient.  According to a Post Courier article in May of this year, Telikom receives about 22% of the K6 billion SOE annual budget which amounts to about K1.3B.  Contact the Telikom office in your area in person and set up a date to install a landline.  If no results in a reasonable time period, go back in person and talk to the next person up the ladder. 
The mobile operators are Digicel and B Mobile.  B Mobile is an offshoot of Telikom.  One of the best decisions the PNG government ever made is that about 10 years ago they allowed Digicel, a private company, in the country to create competition against a bloated SOE telecommunications company.  They did a great job of installing many cell phone towers throughout the country, to the point where I'm guessing 90% of phone users in PNG use Digicel.  It's all prepaid, as people buy K5 or K10 or K20 "flex".  Hardly any monthly plans available.  If you don't need a landline, do without.  Many businesses like landlines because it gives option for sending fax, which is out of date in many countries but still a big thing in PNG.  Digicel has done a great job of creating an effective communication system throughout the country.