It is a sunny day. A cool breeze blows from west to east as you casually SIP a cocktail while putting the finishing touches on the outbound routes for your brand new PBX instance. You gather a crowd around you to showcase your technical prowess and move to place a crystal clear call to your mother. Then suddenly, to your dismay, your call fails when you are abruptly greeted by a 606 NOT ACCEPTABLE from our gateway in response to your initial INIVITE. "Why?", you ask. "Why would SIP.US not only deny my traffic, but have the audacity to tell me that it is frankly NOT ACCEPTABLE"? The answer is simple, you have a janky outbound caller-id. Please ONLY send VALID numeric values in a preferably 10-digit format (for our North American clients).
You may say, "My proprietary PBX costs lots of money and wouldn't let me send an invalid value". Let me assure you, it will. As evidence, I offer you a screenshot of a caller-ID that was successfully saved to a config in a major (unnamed) PBX:
If you send us 1111111111, we will embarrass you in front of your loved ones. If you send us letters, we will embarrass you in front of your loved ones. If you send us special characters such as hyphens or ampersands, we will embarrass you in front of your loved ones. If you have any questions regarding outbound caller ID and the ever important From: header, please feel free to email us and firstname.lastname@example.org