While looking through opensips logs of a customer, sometimes we would see the following:

ERROR:core:parse_via:  invalid port number <110900>
ERROR:core:parse_via:  <SIP/2.0/UDP 1.2.3.4:110900;branch=z9hG4bKabcdef...
ERROR:core:parse_via: parsed so far:<SIP/2.0/UDP 1.2.3.4:110900;branch=z9hG4bKabcdef...
ERROR:core:get_hdr_field: bad via

As you can see, that 6-digit port number is invalid. Furthermore, when sniffing this traffic, we could see that the port number is almost right. The traffic came from port 11090 (one less zero at the end).

Not only the Via header, the ...