Outbound SIP Trunking Services

The DIDWW Outbound SIP Trunking service allows customers to have outbound calling access to the traditional telephony network, including calling to local, mobile, toll-free, short and emergency numbers. This highly scalable and flexible solution supports multiple and diverse clients each with their own custom trunk configuration profiles, and includes fully customizable dial plan and routing rules that may be applied on a per-trunk basis.

Outbound Trunk Creation and Configuration

Outbound SIP traffic is delivered via DIDWW’s high-capacity, global platform, directly peered with a range of selected incumbent local exchange carriers. Configuration, management and monitoring of outbound SIP trunks is available through the DIDWW User Panel.

Step 1. Under the Trunks section, select Voice OUT and click the Add new Trunk button.(Fig. 1).


Fig. 1 Creating a new Outbound Trunk

Step 2. You will be prompted to enter basic configuration parameters at General section (Fig. 2):


  • Friendly name - the friendly name of the trunk.

  • Allowed IP addresses - your system’s IP address from which calls are sent to DIDWW.

  • Allowed RTP IP addresses - your RTP addresses from which audio packets will be relayed to DIDWW.

  • Force symmetric RTP - if checked, the trunk will operate in the Symmetric RTP/COMEDIA mode.

  • RTP Ping - if checked, an RTP ping should be used for connecting the call.


Fig. 2 Outbound Trunks settings

In addition to the basic configuration options, there are advanced options which may be left unchanged. These options are categorized into sections:


Media section allows to specify IP addresses which from RTP are sent to DIDWW (Fig. 3)


Fig. 3 Media section



Encryption is not enabled by default. To enable this feature, please contact sales@didww.com

Encryption allows to use TLS for SIP signaling and SRTP for call content/media packets


Fig. 4 Encryption section


  • Capacity limit - the maximum number of simultaneous calls per trunk.

  • 24 hour limit (USD) - the maximum amount of funds allowed per trunk, per rolling 24-hour period before traffic is blocked on this trunk. However, active calls are not disconnected by DIDWW and may cause your 24h limit to go beyond its set threshold.

  • Voice OUT Trunk usage limit notification - an email notification when 80% of the set limit is reached. Notifications are sent once every 12 hours.


The default 24 hour limit is $3000, the minimum 24 hour limit is $50, and the maximum 24 hour limit is $10000

CLI Rules

There are two possible CLI rules:

  • Send Original CLI - DIDWW will pass the “From” header value from customer system to PSTN gateway without modification.

  • Reject Call - DIDWW will reject the call if value in “From” header is different then the DID numbers allowed in the “CLI settings” list.


Fig. 5 CLI Rules

CLI Settings

The CLI Settings define which DID number(s) may be used as a caller ID for the outbound trunk. These “allowed” caller IDs may be selected from the available DID numbers acquired from DIDWW, and a filter is provided to enable users to list specific DIDs. By default, all DID numbers with “Voice OUT” functionality in the customer’s account may be used as the caller ID on outbound trunks (Fig. 6).


Fig. 6 CLI Settings

Destination Dialing Settings

The “Dialing settings” of DIDWW outbound trunk allows customers to restrict calls to unwanted destinations using the following methods:

Allow All

This method allows calls to all destinations, except to those destinations specified in the listed prefixes.

The following example indicates how to allow calls to all destinations except for: London, UK (4420), Ireland (353), New York, US (1212).


Fig. 7 Allow all, except for the specified

Reject All

This method rejects calls to all destinations, except to those destinations specified in the listed prefixes.

The following example indicates how to restrict calls to all destinations except for the specified: Bogota, Colombia (571), Lancaster, US (1740), Mobile, Denmark (4592)


Fig. 8 Reject all, except for the specified

Step 3. Complete the configuration by clicking Create button on bottom right side

Once the outbound SIP trunk has been created, the SIP credentials for that trunk may be viewed by clicking on the “key” icon under Credentials column (Fig. 9).


Fig. 9 Actions tab and SIP credentials

The “Share” button allows the user to send these SIP credentials to a system administrator for configuration of the Outbound Trunk (Fig. 10). There is an option to view or regenerate the SIP trunk password by clicking on the icons next to the Password field.


Fig. 10 Outbound Trunk credentials

Further configuration of the Outbound Trunk may be performed via the User Panel if required (Fig. 11). The settings for the 24 hour limit (USD) and the Capacity limit may be adjusted by clicking on them. In addition, the trunk Status may be switched on or off to be either operational (blue) or disabled (grey).


Fig. 11 Outbound Trunk management via the User Panel

For more information about outbound dialing: Outbound Dialing

Technical data related to termination services is available here.