SIP Protocol Details

Supported Network and Transport Protocols

DIDWW supports SIP signaling over UDP, TCP, and TLS transports. Communication can be established using the following ports: 5060 for UDP/TCP and 5061 for TLS. Both IPv4 and IPv6 are supported as network protocols for signaling and media.

Signaling Endpoints

Calls can be sent to any of our load balancers. Each load balancer operates as a redundant cluster with multiple nodes that uses the same IP address.

Location DNS A/AAAA record LB IPv4 address LB IPv6 address
New York 2a01:ad00:1:1::44
Los Angeles 2a01:ad00:4:2::54
Miami 2a01:ad00:5:2::54
Frankfurt 2a01:ad00:2:1::19
Singapore 2a01:ad00:6:2::54


DNS SRV acts as a failover mechanism that is used to reroute a call to a backup data center in the event of failure. We recommend enabling this feature if it is supported by your equipment.

DNS SRV record Priority Weigth LB IPv4 address LB IPv6 address LB Location Role 10 10 2a01:ad00:1:1::44 New York Primary
20 10 2a01:ad00:5:2::54 Miami Backup 10 10 2a01:ad00:4:2::54 Los Angeles Primary
20 10 2a01:ad00:5:2::54 Miami Backup 10 10 2a01:ad00:5:2::54 Miami Primary
20 10 2a01:ad00:1:1::44 New York Backup 10 10 2a01:ad00:2:1::19 Frankfurt Primary
20 10 2a01:ad00:1:1::44 New York Backup 10 10 2a01:ad00:6:2::54 Singapore Primary
20 10 2a01:ad00:4:2::54 Los Angeles Backup

RTP and RTCP information

DIDWW uses the following Subnet and Ports for RTP traffic:,16383 - 32767. RTP port + 1 is used for RTCP sending/receiving.


Our systems supports TLS as a secure transport for SIP signaling and SRTP as a media encryption mechanism. All three SRTP key negotiation mechanisms are supported - SDES, DTLS and ZRTP.

SRTP media encryption is disabled by default. Contact our sales team to enable SRTP support for your account.


  • g.711 alaw/ulaw
  • g.729
  • g.723.1
  • gsm
  • telephone-event

P-Charge-Info Header

Customers can append additional technical information using the header described at Our system will store P-Charge-Info value to the CDR, later this data could be used for billing purposes with CDR streaming tool. Header value format is optional.