Reliance Retail's JioFi continued to dominate data card segment with a market share of 91 per cent -- leaving Huawei far behind at three per cent -- during the second quarter of calendar year 2017.The huge lead was attributed to the launch of consecutive free data services by Reliance Retail followed by availability of Mi-Fi data cards at different prices, according to a report by CyberMedia Research (CMR) released on Thursday.Mi-Fis driven by Jio have gained acceptance in tier-2 and tier-3 cities and towns, which could result in erosion of potential broadband base for operators like BSNL."Reliance Jio's Mi-Fi devices (JioFi) have also impacted home router market. Our initial statistics from the channels suggest a decline of 60-70 per cent sales in major cities," said Narinder Kumar, Analyst, Industry Intelligence Practice, CMR, in a statement.The other players were confined to limited market share, like ZTE (three per cent) and Alcatel (two per cent). The report said that the overall shipment of data cards grew to 4 million in Q2 -- an increase of 16 per cent over the 3.4 million units in Q1 and 614 per cent Year-on-year (YoY).LTE/4G data card shipments accounted for 17 per cent sequential growth in Q2 owing to Mi-Fi devices, becoming the most favoured technology.Data card with data-rate of 150 Mbps accounted for 97 per cent of the total shipments with around 92 per cent of them built on Qualcomm chipsets, the report added.