Galaxy S4 defaults to loudspeaker on calls

I take it you've done a factory reset?

It is time to get a new phone. Maybe Samsung S8?

It is hardware problem if factory reset does not help.

When you pull down from the top bar to see your notifications, do you see the Drive Mode shortcut icon? If so, make sure it's not enabled.

It MUST not be Drive mode as you will see loudspeaker icon Is NOT greyed out when you receive or make a call.

I don't think I have a drive mode. It's not in the top bar. Could it be enabled elsewhere and not appear as an icon at the top?

New phone is not the option I was looking for.

The loudspeaker icon is greyed at the start of the call and the speaker is on.
I would expect the speaker to be on only when the icon is lit.

its called hands free mode.

you have to have the full options open..

cf101

I found a hands free mode in the settings area which was off. I enabled it and turned it off again.  I'll have to wait a bit before I can test it by making a call.

I haven't done a reset, that's a bit drastic and a real pain getting everything back where it should be. If I can't find any other way then that will be a last resort.

you reboot it a few times?

mine did that for google hangouts. kept going to speaker after a bit even though it wasnt selected.  rebooted the phone twice and it cleared up

cf101

PS try turning off background processes in dev options.

*background processes
My AVG has recently started popping up a message that too many processes are running. Perhaps it's telling the truth. I thought it was just another advertisement to get me to pay for the thing.
I'm not sure how, but I'll see if I can find what's running.

Try to remove AVG to see whether it helps.

I'd rather check for running processes first.

Is there a way to see background processes that are running?

Enable/disable hands free didn't make any difference. My incoming call just shouted round the office.

there will be many that are running.

I have the same phone here,  and have up to 50 or so apps/ background apps running at a time.

cf101

advanced task killer showed alot of hidden system background apps,  otherwise in settings> app manager you can see

cf101

App manager looks like a good place to start. I didn't realise it showed running processes. There's loads when you scroll it over to the right hand side.

I'm going away testing for a bit.
I may be some time.

Just in case others read this are STILL looking for another possible alternative cause for the phone to always answer a call with speakerphone on so they can toggle the feature on and off at will:
 
My issue was a 3rd party app.
 I knew I had activated my speaker to turn on automatically but had forgotten it was within an app setting of FREE CALL RECORDER. Took me a long time going through anything I could think of including every setting from Samsung first with no luck until I found it again. My fault I didn't make a note of how I activated it, but it makes sense since the Free Call Recorder app only records the other side of the conversation when speaker is on.
 
The setting might be interfering with my Gear 2 Neo bluetooth connectionis the reason I wanted to turn the feature back off to test my theory due to the timing of the issue. Now I can test my Gear 2 Neo with auto speaker on setting disabled. The issue I am having with the watch is when I answer or make a call from it, no one can hear me or I can't hear them or both. Sounds like it is possible related to the 3rd party app setting, so I have been trying hard to get the setting disabled with no luck until now.

Source: https://groups.google.com/forum/m/#!topic/eyes-free/oA_auCRw-Vo

It is a known issue.

Apart from the above, check SVoice settings and re-install apps about Chat/IM like Facebook Messenger.

Somebody woke the thread up and got the site to send me a nagging email.
I said I would be some time.
I will be.

Any recent updates in this?

My S4 is doing the exact same thing now,

Perhaps a comparative list of APPS would help cross off some?

Do you happen to have Advanced task killer? I'm wondering if that is the cause ( if it kills the control process.)

cf101

What is the model no?  GT-I9500?

Have you updated the stock ROM?

https://www.sammobile.com/firmwares/galaxy-s4/GT-I9500/

Actually, it is a bit risky to use an Android phone which has only Android 5.0.1 on it and you might consider replacing your phone with one running Android 7.0.

I don't have an advanced app killer. I tried going through settings to locate the running apps, but I was unable to force stop them. They didn't stop.
Realising that I would have to re-install everything after a factory reset I have reluctantly chosen to go with Jackie Man's workaround and have purchased a nice shiny second hand S7 from eBay. It really is a nice phone. The transfer process was quite easy, plug the two phones together and run smartswitch. Im still trying to remember how to log into everything and had to change my email password which I now need to update on other devices.
Due to a cock-up by my service provider who activated a new sim before posting it to me, the original one deactivated and left me without service for two days. New sim is required because the S7 takes a nano and not a micro. The big downside here is that the transfer copied only my contacts that were stored to phone, just 8 of them. All the stuff on the deactivated sim is inaccessible. The company apologised and gave me a month's free rental. Somehow I am still able to see the full contacts list on the phone, maybe they're cached? So I can manually open each one and copy the details. I can't transfer them to a file as the menu option does not appear and i expect this is due to the dead sim. Im not doing any more to the S4 until I have replicated my contact list. It is giving me a chance to prune it and lose some old numbers that I don't need. Once I have what I need I will do a factory reset and put my spare payg emergency sim in it to see if the loudspeaker fault is cleared.
Buying a new one because you don't know how to fix the old one is a very untech solution, but when the backup software won't recognise your old phone perhaps it is becoming too old.
Some apps didn't copy so I am having to manually comb through everything to make sure I have it all before I reset.

Your contacts should be synced to Google cloud. After you sign on with your Google account in a new phone, your contacts will appear gradually as the sync from Google cloud takes a time to make it.

The best practice is to replace a smartphone after 18 to 24 months as even big manufacturer like Samsung will not update the firmware of their old model which was launched more than 24 months.

Contacts are not synced. Best practice may be to buy a new one every time they build one, but some of us like to know how things work.

When you go to Settings -> Backup and Restore, the setting for Google Backup and Restore will be enabled by default when you first use your Samsung S4 unless you manually disable it.

So, your contacts are in Google cloud. So, when you lost your phone, you can restore the contacts automatically from Google cloud.

Too late for my phone. The few contacts that were saved to the device have copied over to the new one with no difficulty. What I need is the contacts that were saved to the sim. The sim has been deactivated cannot be accessed. Somehow I can still see the contacts, no menu appears to do anything with them, but if I open each one individually I can manually copy the details.
I'm not messing with the phone until I have them all retrieved.

Compfixer, before I do the reset I will go through and list the running services.
We might be able to diagnose the problem.

Services listed in settings as running on the S4.  Facebook does have two appearances and one or two services were appearing and disappearing. This lot were all running when I made the list:

Samsung Wallet
Yahoo Mail
Facebook
Facebook
Messinger
Anti Virus (AVG)
MTP application
RemoteControls
Settings
Bluetooth
SmartCardService
Story Album
S Voice
GooglePlayServices
Media
Recommended Apps
ContextService
S Finder
Samsung Push Service
Email
Unified Daemon (EUR)
Dropbox
TripAdvisor
SamsungKeyboard
System
GlanceViewMk

Go to Settings, then Applications, then S Voice. Uncheck "Auto Start Speakerphone."

Source: https://forums.androidcentral.com/samsung-galaxy-s5/382015-samsung-galaxy-s5-speaker-phone-everytime-i-make-call.html

That doesn't appear as a setting on the s4.
Settings-s voice just gives me the option to force stop it.
Surely if it was being turned on by design then the speakerphone icon would be lit instead of greyed out.
Still copying stuff across, I have a lot of other things going on at the moment and I do have a working phone. It's just going to take me some time to get it configured so it looks the same as the last one.

You will only see the settings within s voice app and it is not to check the setting in application manager.

Run the s voice app and click settings inside the app.

Your instruction said to go to settings, then applications, then s voice which is what I did.
Checking it from the app is something I had already tried way up in this thread. The box is unchecked, Checking it and unchecking it again did not fix the problem.

Try to start your phone in safe mode to check whether the problem is caused by third party apps.

https://thedroidguy.com/2016/08/samsung-galaxy-s7-edge-speakerphone-enables-call-calling-issues-1063544

Do you have ACR app installed?

Jackie, I have a new phone. I will attempt a full factory reset when, and not before when I am ready to burn all the information that the old phone holds. I will post the result.
Until that moment I am not touching the phone in case it loses something I need.
Please read back up this thread even to some of your own suggestions.
THERE IS NO BACKUP.
BACKUP IS NOT POSSIBLE BECAUSE THE SOFTWARE DOES NOT RECOGNISE THE OLD PHONE.
THE PHONE HOLDS DATA AND CONFIGURATION SETTINGS THAT I NEED TO COPY AND DO NOT WANT TO LOSE SO I AM NOT MESSING WITH THE PHONE UNTIL THIS IS COPIED OVER.
WHEN COMPLETE I WILL TRY A FACTORY RESET AND POST THE RESULTS HERE.
I HAVE MORE IMPORTANT THINGS TO DO THAN PISS ABOUT WITH A PHONE AT THE MOMENT SO I WILL GET ROUND TO IT LATER.
I WILL BE SOME TIME.

Before posting anything else please refer back to the section in capitals and check that there is no conflict.

Factory reset will solve the problem.

It is definitely a software issue.

Since moving house I have not yet found the box with that phone in. I am still interested whether a factory reset will solve the problem or if it is a hardware issue. When I find the phone I will try a factory reset and post the results here.
I have not forgotten the question, just unable to locate the phone at the moment.
Please leave this open as the solution or some if the comments and suggestions above could be useful to someone with a similar problem.
Thankyou.

Hope you solve it, I haven't been to determine it on my end, it's an app issue if anything, my does it come and go, haven't been able to narrow it down to a specific app yet,  I kill alot at once. and alot autostart..

a factory reset would delete apps so it may resolve it, but which would be the actual culprit.

cf101

I've just had a reminder for this. I haven't forgotten. I have in fact unearthed my old s2, but that didn't have this problem. I'm still searching for the phone. I'd like to try the suggestions in here and award points. It's been agreed that it can stay open for a little longer. So I'm hoping to be able to locate my phone before the question gets deleted and all these suggestions are lost.
Thanks all for your patience.