Hi @deltaswank, welcome to the community!

Unfortunately, the only custom or vanity number you can request is a Short Code and obviously based on availability.  Short codes (including vanity ones) are generally appropriate for brands or merchants sending large volumes of text as they do have an additional monthly cost.

You can learn more about that here in these Klaviyo documentation (depending on your region):

• Understand US and Canadian SMS sending numbers
• Understand UK, Australian, and New Zealand SMS sending numbers

Hope this helps!

I believe there is another option: acquiring your desired phone number (must be toll-free or short code) elsewhere and porting it to klaviyo: https://help.klaviyo.com/hc/en-us/articles/7117160207131