When the launch date is 14.09.2005, and the frequency is 900mhz and 1800mhz, how many carriers are there?
CREATE TABLE "table1_19246_1" (
  "carrier" text,
  "standard" text,
  "frequency" text,
  "connection_speed" text,
  "launch_date_dd_mm_yyyy" text
);
SELECT COUNT("carrier") FROM "table1_19246_1" WHERE "frequency"='900MHz and 1800MHz' AND "launch_date_dd_mm_yyyy"='14.09.2005';