The strike followed the refusal by the administration of the company to sign a report after negotiations with the workers' representatives, the sources added.
Among other demands, delegates have been pressing for higher wages and other benefits.
According to trade union sources, more than 75 percent of the Mauritel workforce in Nouakchott participated in a sit-in held on Wednesday morning in front of the main entrance to the company's offices.
The firm was left totally paralyzed in 80 percent of its Nouakchott agencies thanks to the strike.
In the other agencies, work activities were significantly affected by the participation of most of their employees in the strike.
The company's services were affected by the strike, which is likely to continue until the demands of the workers are met.
The Mauritel union had written to the management announcing that work stoppages would occur on 30 January and every Wednesday through the course of February and March.