Hi @IniobongNkanga-8038 ,
Is this a new user? If it is are you able to confirm if they are able to make outbound calls?
If this number has not been used before it might be that the number is no on the block of DDI's that is assigned to your account with the Telco.
As a first step I would confirm with the telco if the number is assigned to your account, once confirmed ask them if they receiving a 404 from teams when the number is dialed.
Checking the above will rule out any issue on the telco side or SBC.
Regards,
T