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steve1111

join:2009-09-23
New York, NY
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[General] Receiving calls from cell phones to Voip phone

Landline calls to my Voip phone are acceptable but the quality of calls from Cell phones to my Voip phone are not acceptable. I have enabled codecs G.722 and G.711 but disabled all other codecs. Should I be enabling other codecs? My concern is that by enabling a narrow-band codec, I will then be receiving poor quality calls from landlines.



Trimline
Premium
join:2004-10-24
Windermere, FL

Try placing 711 first, then 722. Not sure what kind of phone this, so let us know as someone may have more info.


steve1111

join:2009-09-23
New York, NY

The Voip phone receiving the cell phone call is Cisco SPA301.


PX Eliezer7
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Hutt River
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reply to steve1111

How do you know the problem is not with the [cellphones] ?

For a true comparison, you would need to evaluate how calls sound from a cell phone to a landline.

If you are in Manhattan the quality of cellphone calls must be pretty bad.

It's bad enough out here in the suburbs where we don't have huge buildings interfering with everything.

-----------------------------------

Are your problems more recent BTW?

Sandy trashed a lot of the cellphone infrastructure AND the landline infrastructure. And although folks don't realize it, the landline network is essential for the [cell] towers to work!

A lot of things are still not upsnuffed in the city.


steve1111

join:2009-09-23
New York, NY
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I think this is a matter of codec and compression and loss of data. I'm quite sure that the problem is with the cell phones rather than the Voip phone; calls received from cell phones are noticeably worse than calls received from landlines. But people do insist on using cell phones. How do I manage with these calls?

During Hurricane Sandy cell phone service was poor to non-existent but now things are back to normal.


PX Eliezer7
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reply to steve1111

My suggestion, assuming good ISP bandwidth:

Preferred: G.722
2nd choice: G.711u (PCMU)
3rd choice: G.729A

said by steve1111:

My concern is that by enabling a narrow-band codec, I will then be receiving poor quality calls from landlines.

G.729A should be OK for landline calls.

It's not as if we are talking about G.726, after all....

-------------------

You have maximized the QoS for VoIP on your router, I assume.

said by steve1111:

But people do insist on using cell phones. How do I manage with these calls?

My secretary and I are [so] sick and tired of receiving garbled cellphone calls.

We know it's [not] on our end, because lots of cellphone calls do come in OK. But some others are awful. And at least around here, it often [does] depend on the cellular carrier they are using.

We are especially sick and tired of them calling our office while they are driving. When people call us to make appointments, we need to talk to them in great detail for 10-15 minutes, yet they are simultaneously trying to not hit a pedestrian, and trying not to have a truck hit them.

So:

It may cost me some business, but if someone calls us on a cheap Drekfone and we can't hear them, or if we realize they are driving a car, we tell them to call us back from a real phone and when stationery. Seriously, we do.

OZO
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join:2003-01-17
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reply to steve1111

said by steve1111:

Landline calls to my Voip phone are acceptable but the quality of calls from Cell phones to my Voip phone are not acceptable.

That's exactly my experience too. Cell phones bring big latency (close to braking whole call experience - people always try to talk at the same time) and many dropped packets. I don't know a solution though. Try different codecs (including GSM, may be) with different orders... Hopefully it will help you somehow. But personally I have no luck with it so far.

Cell phones have intrinsic and big latency, which along with providing low spectrum, puts calls to/from cell phones close to a low edge of any phone experience...
--
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voip_wire

join:2010-07-02
kudos:1

said by OZO:

Cell phones have intrinsic and big latency ...

I am not sure that there is any intrinsic high latency in cellular communication. All EM waves travel at the speed of light. Given a fixed speed of information travel, the time it takes to go from point a to b is purely a function of distance.

Note that this distance is not geomtric distance, but an effective distance. In other words, latency can be large if the signals are improperly routed. However, this is not a fundamental, physical constraint.

I expect that spectrum (as you noted) and transmission losses are the discrminating factors in voice quality. Dissimilar codecs would require an extra decoding - recoding step, perhaps contributing to poor quality.

To the OP, have you tried forcing the gsm codec? The narrow band codecs should not degrade clarity ( in my opinion, but this is a very subjective issue), but would make the audio sound less "natural".

This is partly an educated guess, so I would really appreciate if you report back your findings!

Cheers,
-m


nunya
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reply to steve1111

I believe OZO is on the right track. Cellular calls are inherently latent.
Couple that with the latency that comes with voip, and you get latency pie.
You can probably change codecs all day long and it won't make a bit of difference.
About the only thing you can do on your side is make sure you are using the best voip server for your location. If your voip provider has several servers available, try finding the fastest one from your location.
--
If someone refers to herself / himself as a "guru", they probably aren't.


PX Eliezer7
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reply to voip_wire

If cell towers are busy, some mobile companies switch to GSM Half-Rate [GSM-HR or GSM 06.20] which is 5.6kbit/s

That gives crappy sound.

Reportedly some mobile companies have this as their defaults.

-----------------------------

Also, Nokia offers this as a [customer] option on most Nokia cellphones, the customer can do this by pressing *4720#

Why would a customer do it?

Because it extends battery life.



jimk
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Raleigh, NC
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reply to steve1111

said by steve1111:

I think this is a matter of codec and compression and loss of data. I'm quite sure that the problem is with the cell phones rather than the Voip phone; calls received from cell phones are noticeably worse than calls received from landlines. But people do insist on using cell phones. How do I manage with these calls?

During Hurricane Sandy cell phone service was poor to non-existent but now things are back to normal.

Are you having problems with all mobile phones or just one carrier? There can be a huge difference between providers.

There isn't much you can do about it, other than using the G.722 or G.711u codecs. I would avoid introducing any more compression than necessary.

I suspect the issues you are experiencing are on the mobile phone's side. One or more carriers in your area is probably over-compressing calls to increase capacity. Don't let impressive looking coverage maps make you think call quality on these networks will be perfect (sometimes larger carriers have more capacity issues, so they use more aggressive compression than smaller carriers). Combine this with a poor quality phone or handsfree device, and call quality is going to become very poor.

steve1111

join:2009-09-23
New York, NY
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reply to steve1111

My Voip phone allows for G722, G711u, G729a and several G726's but not GSM. I don't know the carriers of the cellphones used by people who call me. Even if I did know the carriers, what could I do?

I suppose, as time goes by, the percentage of calls from cellphones will increase and the percentage of calls from landliones will decrease, so the overall quality of calls will deteriorate. And there is nothing to do except to curse cellphones - and the carriers.


IPfaxer

join:2010-10-24

have a lot of Cisco SPA2102s deployed so I recall this problem from a couple years ago
G711u for starters and definitely for any fax pass-through
G711a for 2nd choice
don't even allow others

(some carriers do u and not a and vice-versa)

the bandwidth saving codecs are not worth it
make sure your ATA is not clipping "silence" - that will make latent calls sound worse and in and out - check all your settings

also depends on quality of your VOIP carrier
if you are using SIP phones/software also check for silence clipping, etc.


PX Eliezer7
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reply to steve1111

said by steve1111:

I suppose, as time goes by, the percentage of calls from cellphones will increase and the percentage of calls from landlines will decrease, so the overall quality of calls will deteriorate.

It's up to the cellphone customers to complain.

I think there's a general perception that Verizon Wireless has the best network in Manhattan, ahead of AT&T.

From the Wall Street Journal in May 2010:

Dropped calls also happen because of quirks in the way carriers have set up their networks. For example, AT&T Inc. routes calls south of 59th Street in Manhattan to a switch downtown. North of 59th, calls go to a facility in Westchester. So when an AT&T customer crosses 59th, calls can get dropped as the network reshuffles from one switch to the other. Nielsen recorded three fails on or near that dividing line. AT&T declined to discuss coverage at 59th in further detail.

OTOH:

Putting up new cell sites often means dealing with zoning regulations, pushy landlords or community resistance. In the seven years that Chris Hillabrant has been T-Mobile's vice president for engineering in the New York region, he's seen community resistance to new cell towers get "better funded and much better organized."

"Now, they'll bring in their own experts to prove that T-Mobile already has sufficient service or enough cell sites," Mr. Hillabrant says.

So people want a cell phone in their back pocket, but do NOT want a tower in their back yard.

The use of smartphones with their gluttonous demands for data has further strained networks....


Arne Bolen
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reply to PX Eliezer7

said by PX Eliezer7:

It may cost me some business, but if someone calls us on a cheap Drekfone and we can't hear them, or if we realize they are driving a car, we tell them to call us back from a real phone and when stationery. Seriously, we do.

+1
--
My VoIP News


Arne Bolen
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reply to PX Eliezer7

said by PX Eliezer7:

So people want a cell phone in their back pocket, but do NOT want a tower in their back yard.

But they still expect good a good signal.
--
My VoIP News


blohner

join:2002-06-26
Cortlandt Manor, NY
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reply to steve1111

It sounds you are doing what you can. I would avoid double compresseion - even G.729A is problematic when the call comes from CDMA (i.e. Verizon, Sprint).... Full rate GSM would be fine but I have yet to experience that in the US... When I am in Europe Cell Calls generally sound like landline but somehow in the US the carriers get away with compressing the cra.... out of it...

When people call me from their cell I politely tell them unless it's urgent please call me back from your landline once you are home... Doing that every time they call from the call usually get's the message across....
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