No incoming SMS sound heard

[riklar]

Hello
I have two iPhones one is 5 version and the second one is 5s version.
Both are updated to last version of iOS.
In my ver. 5s when incoming SMS arrives the iPhone gives an alerting music.
The problem is with the other iPhone 5 which when incoming SMS arrives no sounds are heard.
I have tried to compare configurations but found no differences existing between the two.
I must missed the issue.
Where should I configure the iPhone 5 to produce the alerting music when incoming SMS arrives.

Thanks
[doublepost=1461082219][/doublepost]I wish to add: no mute is on. It is not in do not disturbe mode

 

[Gav2k]

Are there any other sounds coming out of it? Have you turned the volume up?

 

[readymade524]

Do you have an Apple watch? I've noticed when I'm wearing my watch, I don't get the alert on my phone, just the watch.

 

[Gav2k]

Do you have an Apple watch? I've noticed when I'm wearing my watch, I don't get the alert on my phone, just the watch.

That's normal and expected