Mauritania

Basics
In Mauritania three operators are present and ranked by number of users as following:
 * Mauritel
 * Chinguitel
 * Mattel

Registration
As of the law issued in 2013 and enforced since July 1st 2016, SIM cards have to be registered when being activated and the three operators have been fined in February 2017 for not having this implemented. Expect to show your Passport when buying a SIM card.

Mauritel
Mauritel is partially owned by Maroc Telecom and the largest operator in Mauritania.

Their Pre-paid offer is called El-Jawal and available from their shops.