* Indonesia outperforms on the week amid foreign buying
* Foreigners sell Thai stocks; slump in telecom shares
* Singapore around 2-year high; Malaysia off 2-1/2-year high
By Viparat Jantraprap
BANGKOK, Sept 17 (Reuters) - Indonesian stocks hit an all-time high on Friday on strong blue chips and commodity shares, while the rest of Southeat Asia ended mixed after a strong week marked by brisk foreign buying.
Indonesia's benchmark index, Asia's second-best performer this year, rose 1.3 percent, setting a record high for a seventh straight session.
Foreign investors bought for a sixth straight session, bringing total foreign inflows to nearly $2 billion -- double the total for all of last year. Indonesia was Southeast Asia's best performer in the holiday-shortened week.
"Sentiment was positive, especially for commodity stocks, as the dollar weakened against the rupiah. Foreign inflows are likely to continue next week, which will support stock prices," said John Teja, director of Ciptadana Securities.
Gainers included PT Aneka Tambang Tbk, a diversified mining and metals company, which rose 2.2 percent, and PT Indocement Tunggal Prakasa, the second-biggest cement producer by capacity, which gained 5.8 percent.
Singapore fell 0.4 percent but still hovered near a two-year high. Malaysia edged 0.13 percent lower but at one point touched its highest in 2-½ years. Thailand lost 0.13 percent and the Phillippines shed 0.7 percent after an early rise to a record high.
Vietnam rose 1.8 percent, adding to a 0.2 percent gain the previous session.
Foreign investors bought $111.4 million in Philippine shares this week, but just $1.27 million of Thai stocks, which saw outflows of $33.16 million on Friday, exchange data showed.
In Bangkok, shares in the top three telecom firms plunged after a court froze an auction for third-generation mobile phone licences, threatening a big delay to reforms that were expected to lure more foreign players.
Shares in True Corp Pcl, which owns third-largest mobile operator True Move, fell 25 percent, market leader Advanced Info Service Pcl (AIS) fell 8.7 percent and second-ranked Total Access Communication Pcl lost 14.3 percent.
Singapore-listed Total Access fell 2.8 percent. (Editing by Jason Szep)