Why Don't Cell Phones have Dial Tones? [telecom]

Many cellphone users are still billed by the minute for all connect time. You have to connent to your cellphone network for them to send you a dialtone, so it is cheaper for the user to not have one. That's my guess, anyway.

Cell phones did not have a dial tone. Here is an index to the BSTJ covering their early development (very comprehensive description of all facets of the technology).

For those interested in radio wave propagation, the following may be of interest: January 1953--Comparison of Mobile Radio Transmission at 150, 450,

900, and 3700 Mc

The original mobile phones, back in the late 1940s, were manual. However, in the 1960s an improved system came out where the subscriber sets had dials. Would anyone know if that system offered a dial tone?

***** Moderator's Note *****

The Improved Mobile Telephone System (IMTS) predated the computer revolution, and the dial pulses were sent via tone-based signalling, in real time. Each customer had their own "tip & ring" connection to a Class 5 office at the location of the IMTS terminating unit. Ergo, each customer was connected to their own telephone line when they picked up the handset in their car, which meant that they needed to hear dial tone to know when to dial.

Bill Horne Moderator

[snip]

A couple of years ago one of the news programs had an "anniversary review", so to speak, of cellphone history.

One clip in it (which I wish I'd have been able to record..) showed an early demo of cellphone to a room of reporters.

They were walked through the process of picking up the handset and pushing the key pad.

And... when they picked up the handset, the speaker advised them to, yes, listen for the dial tone.

So the concept, at least, was there. Whether the first practical and marketed units had a dial tone, I can't say. In my own case I had a mobile unit that was silent, but that was already a few years after the rollouts.

The BSTJ article that describes the prototype test set in 1979 makes use of the SEND function in the same way it is used today. There was no dial tone.

(11 meg)

Perhaps the newsclip being shown for the anniversary was for a cordless phone, not a cellphone. Newscasters aren't that accurate on subtle technical matters, and often 'historical' clips aren't the right ones for what they're discussing. For instance, articles on central office telephone operators often have a picture of what is clearly a PBX switchboard, not a central office switchboard (eg

555/556 or 608, which were distinctive designs and AFAIK were only used as PBXs). News articles dealing with railroads often have a photo of a train completely different than the subject of the news story.

P.S. Now I remember that the 1969 Metroliner public telephone did have dial tone, but that was a specialized service. Those phones had automatic handoff from one radio segment to the next, though most of the segments were large.

Interesting guess, but wrong.

The point of a dial tone on a landline is to tell the subscriber that your line has been connected to the equipment at the central office that handles dialed digits. But that's not how cell phones work.

When you turn on a cell phone, it looks for a tower, registers with the tower, and then indicates that it's online, typically by showing a signal strength icon or the like. It pings the tower every once in a while and may switch towers if another tower has a stronger signal. (Things are a little messier with CDMA, but the principle is the same.)

When you make a cell call, the digits you dial are buffered in the phone until you hit send, at which point the phone sends them in a packet to that tower, which then responds by assigning a channel or the CDMA equivalent. The phone then switches to that channel and I believe that all of the call progress tones come from the switch.

So there's no dial tone because there's no point. If your phone weren't already talking to a tower it wouldn't let you make the call.

R's, John

PS: I gather there are phones like the Jitterbug which provide a fake dialtone for the benefit of users who like that sort of thing. But it's generated in the handset, and tells you nothing useful.

What is the function of the dial tone anyway? It is only to tell the calling party that the telephone system is ready to receive the number to dial. It serves no other functional purpose.

There is no benefit to having a cell phone give a dial tone when it is displaying system readiness already. All the calling party has to do is look at it and see that the system is ready for him/her to dial.

Regards,

Fred

There are plenty of blind and visually-impaired people out there for whom this is no help.

I assume without evidence that there is some sort of market for assistive mobile phones which provide auditory and/or tactile cues for those who are unable to see or read an LCD display.

-GAWollman

Not just dial tones but I shut off all DTMF tones etc. from playing on the phone itself. I like my quiet phone.

Apparently not:

The best you can do appears to be a downloadable screen reader app for some models of Nokia phones:

R's, John

In 1986 Western Union introduced a cellular car phone designed for executives, to emulate a familiar office phone (cellular car phones were a new concept then.) It had a landline-style handset and a traditional-looking DTMF pad in the center console. When you took the phone off-hook, and it detected network availability, it played a realistic-sounding dial tone!

That phone was manufactured by E.F. Johnson, which at the time was partly owned by Western Union. It's trunk-mounted transceiver had two TNC antenna connections for the Diversity Receiver inside. I never saw another cellphone with that feature, which greatly reduced signal drop-outs by constantly 'voting' on which antenna/receiver had the best signal. Fading at 800 MHz was a common problem. Audio quality was superb full-duplex FM with negligible latency--much better and natural-sounding than today's mobile phones.