The previous news made many mobile phone users feel unhappy. The reason is that the three major operators have withdrawn from many welfare packages, but they are only useful for new users, but old users have no right to replace them. After the news came out, there were three things that the three operators were interviewed. Some time ago, Unicom and a number of Internet companies launched a series of custom SIM cards, such as Tencent King, Ant Bao, Weibo V, Baidu Shenka, Jingdong Qiangka, B Station 2233, etc. Directed traffic is very affordable for some users with special needs, but these cards are only open to new users, and old users do not. However, the omnipotent netizens have some methods. The netizens have made complaints through the Ministry of Industry and Information Technology, and soon they were notified by Unicom that they can apply for new packages. The basis for complaints from netizens is a document issued by the Ministry of Industry and Information Technology on September 30, 2006, that is, the second requirement in [2006] No. 630: in the same mobile phone attribution, you can choose independently without changing the number. Use all of the company's tariff plans. Netizens broke the news that Unicom old users will be able to change packages However, there are still many students who think that the steps are cumbersome and they are not willing to trouble the Ministry of Industry and Information Technology. The good news is that China Unicom will completely open the policy of changing the new package to the old users at the end of the 10th, but the official has not yet officially responded. In recent years, the introduction of some policies in China has made operators more willing to listen to the public opinion, so that the user experience has been improved a lot. From this aspect, we like the country and praise the operators.
A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire trucks. There are two general types: pneumatic and electronic.
Many fire sirens (used for calling the volunteer fire fighters) serve double duty as tornado or civil defense sirens, alerting an entire community of impending danger. Most fire
sirens are either mounted on the roof of a fire station or on a pole
next to the fire station. Fire sirens can also be mounted on or near
government buildings, on tall structures such as water towers,
as well as in systems where several sirens are distributed around a
town for better sound coverage. Most fire sirens are single tone and
mechanically driven by electric motors with a rotor attached to the
shaft. Some newer sirens are electronically driven speakers.
Fire sirens are often called "fire whistles", "fire alarms", or
"fire horns". Although there is no standard signaling of fire sirens,
some utilize codes to inform firefighters of the location of the fire.
Civil defense sirens also used as fire sirens often can produce an
alternating "hi-lo" signal (similar to emergency vehicles in many
European countries) as the fire signal, or a slow wail (typically 3x) as
to not confuse the public with the standard civil defense signals of
alert (steady tone) and attack (fast wavering tone). Fire sirens are
often tested once a day at noon and are also called "noon sirens" or
"noon whistles".
The first emergency vehicles relied on a bell. Then in the 70s,
they switched to a duotone airhorn. Then in the 80s, that was overtaken
by an electronic wail.
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