samsung s5 SM-G900F call audio delay

[abdu_mka]

Hello
I've just got a used S5 SM-G900F Baseband Version G900FXXU1ANC7 and I have noticed that there is a large amount of delay when calling !
the G900F is the European version, it doesn't connect to LTE but that doesn't matter to me.
My carrier is Ultra Mobile, its a mvno that uses T-mobile network
here is the delay shown in this clip : https://youtu.be/7Ko6ogf4i-c

I have tried my SIM in another phone and there is no delay
any ideas ?
-----------------------------------------
edit :
thank you so much ironass , after the manual update there is no delay in the call audio

 

[ironass]

My first suggestion would be to update your firmware from the very old Android 4.4.2 to the latest, Android 6.0.1, for your model of phone, CSC and Product codes, as per #1.11 of 42 Galaxy S5 models - Dummies Guide to see if that helps.

 

[abdu_mka]

thank you so much for the great article.
so now I want to manually update my S5, but I couldn't find the exact same version "G900FXXU1ANC7" neither here : Firmware for Samsung sm-g900f - SamMobile nor here : https://samsung-firmware.org/model/SM-G900F/page/9

how can I know which other version is compatible ? and will the update wipe all my data ?
thank you again @ironass

 

[ironass]

Your need to re-read #1.8 of the guide again. Look for your Product Code if there is more than 1 version.

 

[abdu_mka]

thank you , I reread it 3 times with no luck!
I had one question , the phone info app gives the following :

phone model SM-G900F
device type : klte
product name : kltexx
made in korea
knos warranty void :0x0
product code : SM-G900FZWABTU
CSC country : UK $ IRE/ GB
csc version G900FOXA1ANC7

can I download this via oden ? :

Model Name: Galaxy S5
Model: SM-G900F
Country: France (SFR)
Firmware Version: G900FXXU1CPI9 
OS: Android Marshmallow
OS Version: 6.0.1
Build Date: September 07,2016
Changelist: 8538464 
PDA: G900FXXU1CPI9 
CSC: G900FSFR1CPI1

 

[ironass]

What is your Product Code?

 

[abdu_mka]

Sm-g900fzwabtu

 

[ironass]

Sm-g900fzwabtu

You have the U.K. unbranded firmware Product Code, BTU. Here is the latest firmware...

Model SM-G900F
Model name GALAXY S5
Country United Kingdom
Version Android 6.0.1
Changelist 7182592
Build date Tue, 30 Aug 2016 10:47:10 +0000
Security Patch Level 2016-09-01
Product code BTU
PDA G900FXXS1CPHW
CSC G900FOXA1CPE1

 

[abdu_mka]

its currently downloading ,
but one last question, will it break my phone if I downloaded another region firmware ?

 

[ironass]

its currently downloading ,
but one last question, will it break my phone if I downloaded another region firmware ?

See the warning in #1.11 of the Dummies Guide but it will not, "break", your phone as such.

 

[abdu_mka]

thank you so much ironass , after the manual update there is no delay in the call audio