Number always busy

[CockneyRebel]

When I call a certain number I get msg saying line is busy when I know for a fact it isn't. Checked to see if number is blocked which it is not checked number deleted number reinstated number all to no avail. Put sim into another phone no problems just my Samsung A15 with the problem. Any ideas much appreciated. 

[BandOfBrothers]

Hello @CockneyRebel 

Welcome to the Samsung Community Forum. 

I'd suggest to delete the contact and also delete all calling history, and Clear cache from your phone app by long holding down on the app then i,  storage and clear cache , soft reboot the phone by turning it off and on and then try dialing the number from the keypad to see if that works. 

If i can be of any further help please don't hesitate to ask  😎 

[CockneyRebel]

Thanks for advice unfortunately still says line busy.