"The network quality is bad; Zain and other operators lack transparency in their billing systems, customers lose coverage all the time, there are drops in the middle of communications, and most often help-lines numbers are hardly answered," said Iro.

For Zain, the option seems to be a network upgrade by the end of the year, or it may quit the market, though the details of the original license are not known.

"Probably, according to the original licence conditions, Zain can automatically apply for a licence renewal and it would probably be granted, but stricter quality measures may be set in place or clauses regulating that quality (of voice services)," said Dobek Pater at Africa Analysis.

But the issue of quality of service is not isolated to Zain or Moov -- it's common in Africa, given that data users are rising, most mobile operators have become the largest ISPs (Internet service providers), and network investment is not matched with sales and marketing.

In fast-growing markets, the demand (particularly in the larger urban centers) often outstrips supply. Operators have begun to push data services, which places further pressure on the quality of voice, and in the narrow band, operators use the same voice networks to deliver data services, added Pater.