Unable to view or add SMS message Center Number

I am experiencing "Error Performing Request Unknown error" error on my iPhone 5s each time I dial *#5005*7672# or **5005*7672*+xxxxxxxxxxxx# .

Handset : Iphone 5s / SW : iOS 12.4 / iOS 12.3

Issue : Unable to send SMS and configure SSMC

When I insert a alternate SIM - Send message - Works however error on dealing *#5005*7672#

Reseted Network settings - Unable to send SMS and error on dealing *#5005*7672#

Master reset - Unable to send SMS and error on dealing *#5005*7672#

Appreciate your advice / Solution