| 摘要 |
The method for long distance call by checking a permitted grade by local code includes a first step for alloting channel of hook off intra line port and analyzing dialed number, a second step for checking wherher a grade of intra line subscriber is connected with a subscriber line, a third step for tramsmitting line's busy signal when the grade is low, a fourth step for checking and connecting free subscriber's line, a fifth step for checking whether the number is international subscriber dialing code, a sixth step for checking whether the grade of subscriber is gualified for international calling, and a serenth step for checking that the number is special service code.
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