As already mentioned, Craigslist does not support every kind of phone number. This was done with the main purpose of trying to stop, or at least prevent, people from abusing the verified account system. Only a few kinds of numbers are truly compatible with Craigslist. Phone numbers that have been stated to officially work with Craigslist are standard landline and cell phone numbers. However, when you take a look in details at which specific kind of numbers are supported, In reality there is much more to it than just this. There are many cell phone companies which will not work. Prepaid cell phone sims are the main culprit and do not work. Of course, Craigslist does not mention or state this anywhere on their website. It is easy to understand why this is the case because Craigslist is aware that some users will buy them just to make phone verified Craigslist accounts. Furthermore, VOIP landlines will also not work. VOIP numbers are also blocked because Craigslist most likely considers that they are too easy to get access to due to their low price and will be abused by people just to verify accounts.
If you are looking to make your own phone verified accounts, you will have to make sure that whatever number you use does not fall under the category of b
