* Q3 net loss 87.1 mln riyals vs net loss of 122.1 mlnriyals a yr ago * Q3 revenue 395.6 mln riyals vs 315.8 mln riyals a yr ago * Subscribers top 1 mln, up 26 pct from a year earlier * Average revenue per user rises 8.4 pct to 121 riyals By Matt Smith DUBAI, Jan 16 (Reuters) - Vodafone Qatar, anaffiliate of Vodafone Group, reported a narrowingthird-quarter loss on Wednesday as its subscriber base rose by aquarter and revenue per user grew. Vodafone, which ended Qatar Telecom's (Qtel)domestic monopoly in 2009, made a third-quarter net loss of 87.1million riyals ($23.92 million) in the three months to Dec. 31,according to Reuters calculations. That compares with a loss of 122.1 million riyals in theyear-earlier period. The operator's financial year starts onApril 1. Quarterly revenue was 395.6 million riyals, up from 315.8million riyals a year ago. Vodafone Qatar launched post-paid contract services in June,which the operator hopes will help woo subscribers from Qtel andimprove margins. Customers on post-paid contracts are typicallywealthier and spend more on telecoms as well as being lesslikely to switch operators. Vodafone had 1 million mobile customers as of Dec. 31, up 26percent from a year earlier. Third-quarter average revenue per user (ARPU), a key metricfor the telecom sector, was 121 riyals, up 8.4 percentyear-on-year. Vodafone, which owns 23 percent of Vodafone Qatar, inNovember extended a contract to manage its Qatari affiliateuntil 2018.