Issue

Please find possible options for troubleshooting inbound telephony below:

Product

• Voice

Resolution

1. Inbound number (DID) not bound to correct Distribution Group Check your Distribution Group IP address settings in Voice Management App.
   
2. Firewall or PBX not configured for CM inbound trunk IP addresses Inbound traffic is routed from our dedicated inbound platform. Please allow incoming traffic from:
   
   Inbound10:
   188.94.184.98
   188.94.184.99
   188.94.184.100
   
   Inbound20:
   188.94.185.98
   188.94.185.99
   188.94.185.110
   
3. No correct response to SIP OPTIONS keep alive messages
   When making an inbound call to the number hosted with CM and if a triple tone is received with a message stating that the numbered dialed is not available it could be that your PBX is not correctly responding to our SIP OPTIONS keep alive messages.
   
   Our inbound platform is sending these keep alive messages which need to be acknowledged by a 200 OK from the customer PBX instance. These message are sent from sip.cm.nl
   This is the principle by which our gateways check if the inbound trunk is still available.
   After updating your config, please wait 3-5 minutes before retesting since our platform requires a successful response in order to resume inbound call delivery.
   
4. Inbound number format
   The number format for inbound calls is always with the "+" symbol.