Change to SIP response code for denylisted origin numbers

What's happening?

Customers with voice transit enabled should be aware that beginning March 20, 2025, we are changing the response code for a prefix that comes from a denylisted origin number from 503 to 603 on the BWI Legacy Network.

What do I need to know?

Beginning March 20, 603 sip responses will be sent for INVITE messages that are blocked due to denylisted origin numbers. This change may take a few days to fully take effect.

We are making this change to avoid the retry typically triggered by a 503 response.

What do I need to do?

The 603 response is a standard reply that most SIP devices can already handle correctly, so most likely no action is needed. If your SIP device cannot handle 603 responses, please configure your device in advance of March 20.

Questions?

Please open a ticket with your Bandwidth Support Team or hit us up at (855) 864-7776!