Each customer site links its own internal network to the Telseon system through a single dedicated switch, a far simpler route than the clumsy path of the old telephone system.

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But the carrier, which has a much smaller European route map than United, has some flexibility to switch to Boeing 767 jets, and a spokesman said it tries to do so in the winter.

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All power wasn't lost, because a second switch remained active, allowing some electricity to flow over an alternate route.

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Reframe or capture missed photo opportunities on the way back down, then retrace your route on the metro, heading back south to San Antonio station, where you will switch to the east-west Line B.

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