Japan's largest mobile operator NTT DoCoMo is taking phones from Sony, Sharp and Fujitsu for its main winter product line-up, with the exclusion of Samsung, reports Reuters.
Reuters, which has spoken to "sources familiar with the situation", points out that Samsung supplied one of the two models, along with Sony, for NTT's main summer range.
Those sources say Samsung is being excluded this winter as it lacks a new flagship model, and after its Galaxy S4 "fell short of DoCoMo's summer target", despite strong sales for Sony's Xperia A.
DoCoMo is expected to offer phone discounts during a winter promotion campaign, just like it did this summer.
A big jump in handset sales at Sony, assisted by the NTT discounts, helped Sony's mobile and PC division return to profit in the last quarter.
For the first quarter (ending June), Japanese firm Sony said total group sales totalled around £11.5 billion, which was up 13 per cent on the first quarter last year.
Sony said it sold 9.6 million smartphones - including the Xperia range - in the three month period, which was a healthy increase on the 7.4 million smartphones it sold in the same quarter a year ago.
This led to the company seeing an operating profit in its mobile and PC unit, totalling £40 million, after it made a loss last year.
Sony's total group operating profit increased to £244 million, while its net profit came in at a slender £23 million.
In the summer NTT campaign, says Reuters, the company is said to have sold under 700,000 Samsung phones, short of a 1 million target, as opposed to the 1.3 million Sony Xperia A handsets sold in the same campaign.
Although NTT will still sell new Samsung phones as they come onto the market, the fact that Samsung, the world's biggest smartphone manufacturer by sales, is being excluded from NTT's main winter drive, will be a surprise in some quarters.