CREATE TABLE table_203_603 (id DECIMAL, "service" TEXT, "service id" TEXT, "bit rate" TEXT, "audio channels" TEXT, "description" TEXT, "analogue availability" TEXT)

the service with the least bit rate
SELECT "service" FROM table_203_603 ORDER BY "bit rate" LIMIT 1
SELECT "service" FROM "table_203_603" ORDER BY "bit rate" NULLS FIRST LIMIT 1