question: With all the processes that cell phones carry out, how are they completely silent?
comment: Noise in electronics is almost exclusively from moving parts. In a computer, this has historically been fans, disc drives and hard drives. Phones typically lack all three of these sources, using passive cooling for components and solid state storage solutions. There's still electronic elements that produce sound, but in phones, that's typically below ambient sound levels.
passages: Section::::Technology.:Signaling.
  
  NMT voice channel is transmitted with FM-modulation and NMT signaling transfer speeds vary between 600 and 1,200 bits per second, using FFSK (Fast Frequency Shift Keying) modulation. Signaling between the base station and the mobile station was implemented using the same RF channel that was used for audio, and using the 1,200 bit/s FFSK modem. This caused the periodic short noise bursts, e.g. during handover, that were uniquely characteristic to NMT sound.
  
  Section::::Technology.:Security.
   Another study, conducted among 3,630 UK companies in March 2013, looked into the amount of time customers spend on hold while making calls to business. The average hold time was 33.48 seconds. During this time spent on hold, 34% of businesses left callers listening to silence, 26% played music, 26% played beeps and 7% used on-hold marketing messages.
   Section::::Reception.
  
  Section::::Reception.:Commercial.
   Dead zones can be filled-in with microcells, while picocells can handle even smaller areas without causing interference to the larger network. Personal microcells, such as those for a home, are called femtocells, and generally have the range of a cordless phone, but may not be usable for an MVNO phone. A similar system can be set up to perform inmate call capture, which prevents cellphones smuggled into a prison from being used. These still complete calls to or from pre-authorized users such as prison staff, while not violating laws against jamming. These systems must be carefully designed so as to avoid capturing calls from outside the prison, which would in effect create a dead zone for any passersby outside.
   In November 2011, a survey was conducted among 2,000 UK consumers concerning phone calls made to businesses. Findings included:
  
  70% of consumers are put on hold for more than 50% of their calls; 68% of consumers are put on hold for longer than one minute; 73% of consumers want to hear something other than beeps or silence while on hold; 72% of personal calls to businesses are made at home on a landline; 60% of consumers are in front of a computer while on hold.
   Section::::Maritime Mobile Service.:Silent periods.
   An automatic 24/7 detect and locate solution such as this bypasses the weaknesses inherent to jamming (e.g., phones of facility workers can be jammed); managed access solutions (surrounding neighborhoods can be affected by the "bleed" from these systems preventing bystanders from making calls and/or not all makes of phones are subject to call intercept); and phone sniffing dogs (this solution only works when the dogs are patrolling). New solutions have been introduced to the market that provide such automated 24/7 detect and locate capabilities.
   Section::::Recording.
   A variation on selcall transmission that includes a status code is for the transmitting device to insert one or two tone periods of silence between the preceding tones and the status tone; the so-called status gap. Another variation is to prolong the status tone by another tone period; the so-called two tone-period status tone.
  
  Section::::Proprietary Implementations.
  
  Motorola's name is "Select 5" in sales brochures for obsolete equipment marketed in Europe such as Syntor mobiles, Syntor X mobiles, Mitrek mobiles, Mostar mobiles, and Maxar mobiles.
  
  Section::::Proprietary Implementations.:As push-to-talk identifier.
   Another solution is the use of ferromagnetic cell phone detectors. This technology detects the presence of the ferrous metal components (antenna, vibrator, speaker) that are in cell phones. The reliance is then not on the location of signals, but in the recognition of the physical phone itself which cannot be masked by internalizing or hiding on the person.
   Digital switches encode the speech going on, in 8,000 time slices per second. At each time slice, a digital PCM representation of the tone is made. The digits are then sent to the receiving end of the line, where the reverse process occurs, to produce the sound for the receiving phone. In other words, when someone uses a telephone, the speaker's voice is "encoded" then reconstructed for the person on the other end. The speaker's voice is delayed in the process by a small fraction of one second — it is not "live", it is reconstructed — delayed only minutely.
   A CNN survey found that 70% of callers in the United States who are holding the line in silence hang up within 60 seconds. A study by North American Telecom found that callers hearing music on hold will stay on the line 30 seconds longer than callers experiencing silence, and callers hearing commercials on hold will stay on the line for up to 3 minutes longer.
  
  In November 2011 an omnibus survey of more than 2,000 UK consumers highlighted several key figures related to modern business
   When all channels at a VOC enabled site are in use, or a single channel site gets a call request, there is specific data sent out over the control channel to notify all radios at the site that the control channel will be momentarily switching to voice channel mode. Once this happens radios resort to their programmed information which contains timing values that determine what to do once the timer runs out and there is still no control channel (Signal "Out of Range," switch sites, etc.) available.
   The off network feature on the iDEN phones work for up to a six-mile radius and will communicate with all other iDEN phones in the area on the same channel and code access number.
   communications and specifically to on hold messaging. Conducted by ICM on behalf of audio branding specialist PHMG (company), the survey found:br
  
  70% of consumers are put on hold for more than 50% of their calls; 68% of consumers are put on hold for longer than one minute; 73% of consumers want to hear something other than beeps or silence while on hold; 72% of personal calls to businesses are made at home on a landline; 60% of consumers are in front of a computer while on hold.
  
  Section::::Recent trends.
   Section::::The No Agent Available (NAA) message.
  
  One solution to silent calls is for marketing organizations to play a recorded message to the consumer explaining why the call was silent and why no agent was available. The industry, led by the DMA, resisted this for a long time because it was assumed that it would be termed illegal under article 19 of the Privacy and Electronic Communications (EC Directive) Regulations 2003 (PERC):
  
  "Use of automated calling systems
   TADs with digital storage for the recorded messages do not show this delay, of course.
  
  Section::::Pure voice operation.:Remote control.
  
  A TAD may offer a remote control facility, whereby the answerphone owner can ring the home number and, by entering a code on the remote telephone's keypad, can listen to recorded messages, or delete them, even when away from home.
   Section::::Impact on society.:Human behaviour.:Etiquette.
  
  Mobile phone use can be an important matter of social discourtesy: phones ringing during funerals or weddings; in toilets, cinemas and theatres. Some book shops, libraries, bathrooms, cinemas, doctors' offices and places of worship prohibit their use, so that other patrons will not be disturbed by conversations. Some facilities install signal-jamming equipment to prevent their use, although in many countries, including the US, such equipment is illegal.
   Section::::Interference and limitations.
  
  BULLET::::- Professional wireless microphones used the 700 MHz band until 2010 when they were made illegal, but equipment still exists in use that may interfere with 3G and 4G technologies.
   Cell phones are limited to a equivalent isotropic radiated power (EIRP) radiated power output of 3 watts, and the network continuously adjusts the phone transmitter to the lowest power consistent with good signal quality, reducing it to as low as one milliwatt when near the cell tower. Cell phone tower channel transmitters usually have an EIRP power output of around 50 watts. Even when it is not being used, unless it is turned off, a cell phone periodically emits radio signals on its control channel, to keep contact with its cell tower and for functions like handing off the phone to another tower if the user crosses into another cell. When the user is making a call, the cell phone transmits a signal on a second channel which carries the user's voice. Existing 2G, 3G, and 4G networks use frequencies in the UHF or low microwave bands, 600 MHz to 3.5 GHz. Many household wireless devices such as Wifi networks, garage door openers, and baby monitors use other frequencies in this same frequency range.
   Modern mobile phone networks use cells because radio frequencies are a limited, shared resource. Cell-sites and handsets change frequency under computer control and use low power transmitters so that the usually limited number of radio frequencies can be simultaneously used by many callers with less interference.
   Modern mobile phones use a multi-microphone design to cancel out ambient noise from the speech signal. Software is used to subtract the sound captured by the microphone(s) placed furthest from the mouth, from the microphone closest to the mouth, which produces a much clearer speech quality.
  
  Section::::Active vs. passive noise control.
   Many silent calls are a result of process known as pinging. This is very similar to an Internet Protocol (IP) ping, where the intention is to see if there is life at the destination. This is often used by data cleaning companies as a method of removing dead telephone numbers from old lists. Each number is dialed and immediately dropped if the call is connected. If the call is not dropped quickly enough, it may result in a short ringing signal.
  
  Section::::Telemarketing and the UK DMA.
   Section::::Reception.
   Hundreds of Pixel 2 and Pixel 2 XL owners have been complaining of high-pitched and clicking sounds coming from the phone. Google investigated the issue and recommended turning off NFC to temporarily fix the problem until a software update comes out. The November security patch fixed the clicking sound as well as the KRACK WPA2 Wi-Fi security issue, however, it did not fix the buzzing sounds heard during calls on some devices. Google has promised a fix in a future update.
  
presuppositions: Phones are completely silent.
corrections: Phones have electronic elements that do produce sound, but that's typically below ambient sound levels.
raw_presuppositions: Phones are completely silent. Phones are completely silent.
raw_corrections: Phones have electronic elements that do produce sound, but that's typically below ambient sound levels. Phones have electronic elements that do produce sound, but that's typically below ambient sound levels.