Transferring your phone number to a different provider is not something you can do instantly. In most cases, it takes between 5-7 business days to port a phone number from one provider to another.
Number porting time depends on the complexity of the request, the type of number being ported, and your existing carrier. Due to vacations and network maintenance, telecom operators may also introduce porting block days.
Although porting typically take 5 - 7 days to complete, they may take up to 4 weeks.
Therefore, you must first consider the procedure for transferring your phone number from one carrier to another in order to understand the average porting time.
Many countries have laws requiring telephone services to permit users to transfer their numbers to different service providers. The regulations are not always simple to uphold, though.
Some VoIP providers and telephone companies are unwilling to let consumers go and make the procedure as challenging as possible. Businesses could find it detrimental to their income if there is a long lead time for transferring a number, and some might conclude the trouble is not worth it.
Having stated that, there shouldn't be any downtime for your phone number. The changeover time issue is a concern, however, the change should be immediate when the company moves the phone number to a new carrier.
The transfer time also depends on the service provider. The ones who are quick in transferring the number if everything goes well include Community Phone, AT&T, Verizon, Google Voice, Vonage, and T-Mobile.