A telephone number may have been linked for years to care, family, customers, accounts and recovery codes. Losing it can therefore have consequences far beyond temporarily being unable to make calls.
Before changing provider, establish who holds the number, what agreement exists and which details are required for porting. Do not blindly cancel the existing line before the number transfer has been confirmed.
That depends on the provider and type of connection, but usually the new provider starts the transfer together with the number holder. Use the exact registered details and follow the required verification process.
Only once it is clear how the port will be carried out and the new provider has confirmed which step is required. Ending the old connection too early can complicate the transfer or even cause the number to be lost.
The number holder, customer or account number, provider, contract details, porting ticket, relevant dates and the new destination. Also record where voicemail, forwarding rules or recovery codes need to be changed.
If that turns out to be appropriate after the situation has been investigated, the organisational and financial explanation is available under Independence and technical continuity.