Landline phone not ringing

Hi, I am new to this forum so please be gentle with me.

I have just been made aware of a problem with my cordless landline telephone in that it no longer audibly rings for an incoming call.  When I run a test call from my mobile, I can hear a ringing tone and the landline handset shows an incoming call (which I can answer), but there is no ringing sound.

I've checked the settings on the handsets, which are fine and I have tested base set and phone in another house and it works fine. 

Please advise what I should do next to try and get the issue diagnosed and fixed.

Thanks

Jeff