### Description

I've recently spent some time debugging a case with JsSIP and usernames in form of a generated string which can be both upper and lower case letters plus digits.

On BYE from callee to JsSIP, it responded with a "404" and "Request-URI does not point to us" in the console while debugging. JsSIP is using the Contact returned in the 200 OK to REGISTER (which is transformed to all lower case) for new outgoing INVITE. It does not match this against the one used in BYE correctly, and return "404".

I see there is a setting in the registrar about this: ``` 3.11. case_sensitive (integer) If set to 1 then AOR comparison and also storing will be case sensitive, if set to 0 then AOR comparison and storing will be case insensitive. This is recommended. This parameter can be modified via Kamailio config framework.

Default value is 0. ```

Since the RFC states that username should be handle case-sensitive, maybe it would be smart to change this default? ``` Comparison of the userinfo of SIP and SIPS URIs is case- sensitive. This includes userinfo containing passwords or formatted as telephone-subscribers. ... The URIs within each of the following sets are not equivalent:

SIP:ALICE@AtLanTa.CoM;Transport=udp (different usernames) sip:alice@AtLanTa.CoM;Transport=UDP ```

#### Reproduction

Make a registration with a username containing both upper and lower case characters. It will be stored in all lower case.

### Possible Solutions

Change default value.

Regardless of the outcome on this case - at least now there is a note about it here too.