I want to keep my old phone number

[MSF]

@Gillian_2220392  The answer is here: https://help.smarty.co.uk/en/articles/1062823-transferring-my-number

Hope this works for you.

[JJP2]

So, text PAC to 65075 from your OLD SIM.

You will get the PAC (Porting Authority Code) by text within 60 seconds.

The PAC code is valid for 30 days 

Give the PAC code to Smarty via your account dashboard when you activate your Smarty SIM.

The transfer of your number from your old network to Smarty will take one or two business days (Numbers do not port during the weekend)

NB : This is the Smarty community forum, populated by Smarty customers like you and I.

https://help.smarty.co.uk/en/articles/7019273-keeping-your-number 

*THE above article says to use your date of birth when requesting a PAC code. This isn’t necessary, just text PAC to 65075 from your current network’s SIM.

[Chalkychap]

I believe some service providers ask for DoB with a PAC request, when using the 65075 method. 

Intriguing that someone, somewhere decided the SMS should arrive within 60-seconds, given the GSM SMS standard doesn't guarantee delivery of a message - though most SMS messages are usually pretty quick, but not always.