Q: iPhone 4S dropping network and data at random

Hi, does DOCOMO have a good 3G network that will work all over Delhi (if you are from Delhi)? I was thinking of changing it to Aircel, but I do not know if anyone has tried that.

New problem: In the morning when I woke up my phone showed Invalid Sim....I had to switch it off and then turn it back on, removed my sim and then put it back again to get the network. Anyone else having the same problem?

yeah this happens with me all the time! i am from Pakistan though!! i dont know what the heck is wrong with this!! spent so much money on it and its useless:@

Same problem Romania. I think it's the software!! We have to wait and see.

I have the exact same problem. My iPhone (4S 64 gb factory unlocked) has been dropping phone-calls from time to time. Sometimes it works flawless for phone calls over 60 min but sometimes it drops just after 2-3 min.

From yesterday I started to get the "Invalid sim"-error. Changed my SIM card today but I can't say that I have particularly high expectations.

From Sweden with op: Telia.

I see the Invalid SIM error first up every morning. I turn off and on the phone. Signal appears usually all 5 bars. The first call usually goes through. Second call is a "Call Failed". In some cases even the first call is a "Call Failed". The signal now goes from 5 to 1 to 0 bars. Now the message is "Searching".. The signal may come up with all 5 bars or "no Service" the next call goes through. The next call is "Call Failed".. Erratic behaviour..

In the diag info Settings- general - about - diag I see a lot of these messages "modem reset: Call state out of sync"

What I tried..

The tape on sim holder solution..

Reset network settings..

Turn off.. On phone..

Full restore as new phone..

Changed SIM card three times..(provider Airtel India thought I was crazy)

A new SIM card did the trick. I have concluded that IPhone 4s works with certain type of SIM cards only.

A micro sim from airtel did not work. A cut-up mini SIM worked.

Which network Andrei?

I have the same problem on Cosmote - monthly subscription and Vodafone prepaid microsim.

Salutare!

Hi! Turn off the menu settings automatic diagnostics and everything will be good!

Hi, how do you do that? Do you mean turn off send diagnostics to Apple? Because, I already had that switched off.

Hi Venkat,

I too have an Airtel sim and all the problems you mentioned above. Did you ask for a particular sim from Airtel, say 64K or 128K, or just tried your luck with any other sim? Also, how long does it take for the new sim to start working?

Thanks.

Hello everyone. I'm from the Philippines and have the same problems with everyone here with the iphone 4s. Have done every suggestion posted here but unfortunately  none worked. Frustrated, i bought an android phone, the samsung galaxy note. Left my iphone 4s in my table with a sim inside and switched on waiting for an update that may make the phone work again. Every now and then the phone would display "sim failed" or something and i would switch it off then on again. This occured for several days. Then i noticed a couple of days ago that the phone had not displayed the "sim failed". So i grab it, the iphone 4s of course, and started using it again to make sure if everything is working fine. Alas! It's over a day now and my iphone 4s is working perfectly fine. No more problems. Some kind of miracle? Huh?!

@vlad - How do u do that ?

@venkat - Can i have ur contact number or email. I need some more information..

I have posted in here before about switching sim card and my 4S starts to work normally again. Sadly it does for a day and it goes back to Sim card faliure and constantly searching for network. I have since switch my phone for a new 4S and this particular phone is so new it comes pre-installed with 5.0.1. It is working good. However, some time I got up in the morning and find my phone with Invalid SIM card message.

My first 4S was bought in Melbourne Australia. Used in Cambodia with Mobitel with version 5.0. My second 4S was bought in Washington US and I brought it back to Cambodia to use with the same Mobitel sim card. It is working very well however I notice while driving, my 4S, every now and then, go to Searching mode and suddenly cut of my call. I am sure it is affecting the signal during switching of Antennas.

My girlfriend 4S, bought at the same time in Singapore preinstalled with 5.0 is working flawlessly here in Cambodia with Mobitel. I told her not to upgrade for precautions. All sims cards were used in various phone from 3GS to 4 to Nokia and Samsung, all works fine. This is a phone, probably software issue that Apple needs to fix. I know how frustrated you are, believe me I travel a lot and need my phone to work perfectly. Apple should address this issue considering they are selling it by the millions everyday. I have sunmited a bug report. I urge people here to do the same because complaining here doesn't change anything.

Goodluck.

Hi again i have a very simple solution to your problem, i solved my problem through throwing my phone off a 10 storie high building but i do notvsuggest you do that

here is what you should do,  get your or your frinds car try reving it to feel the rpm place your phone under the tyre with coushion under the phon, because its a expensive phone. and deserves respect. put the car in reverse not thinking of phone and put your foot down, you should get an immediate frusturation relieved. got to a phone shop and get a phone that not apple.

or simply try by building method

  @Vinothkk @chintanfromtoronto and All the SIMs that i used were 64K.

I guess iPhone likes straight lines on its' SIMs :-)

Salut. I'm using Orange Romania. And today i'm going to change my sim. I will keep you updated.