Breadcrumbs

Number requirements for outbound calling

CM.com requires all numbers for outbound calling to be formatted using E.164, where the initial + sign is optional.

To / Request URI - The To-header and the Request URI should contain a valid number in the user part of the SIP URI.

From - The From-header should contain a valid number in the user part of the SIP URI, unless the P-Asserted-Identity-header or Remote-Party-ID-header already contain a valid number.

P-Asserted-Identity - The P-Asserted-Identity-header, when present, should contain a valid number in the user part of the SIP URI.

Remote-Party-ID - The Remote-Party-ID-header, when present, should contain a valid number in the user part of the SIP URI.

When a P-Asserted-Identity-header is present in the SIP INVITE, CM.com will use this number as the presented CLI. When a Remote-Party-ID-header is present and no P-Asserted-Identity-header is present, CM.com will use the number in the Remote-Party-ID-header as the presented CLI. In all other cases, CM.com will use the number in the From-header. At least one of the headers (From, P-Asserted-Identity or Remote-Party-ID) should contain a valid number for CLI presentation.

For anonymous calling, a valid CLI should always be present. For more information please visit the Anonymous calls Knowledge Center page.

If your PBX does not have means to send a (valid) CLI in any of the mentioned headers, please refer to the configuration of your SIP account in the Voice Management App (link). Here you can configure one of the DID on your account as the Default CLI.

STIR/SHAKEN

For some countries, STIR/SHAKEN is required to provide attestation on the CLI used for calls. CM.com takes care of signing calls with a valid Identity for the countries that require this. Please visit the STIR/SHAKEN Knowledge Center Page.

FAQ

Can I use a mobile number as a CLI?

Using a mobile CLI over fixed connections is permitted under strict regulations if three cumulative conditions are met:

  1. Lawful Use: The user must be the legitimate holder or have explicit, verifiable consent from the holder.

  2. Reachability: The mobile number must be active and correctly terminate return calls on the user's platform.

  3. No Misleading: Use for fraudulent purposes or unverified telemarketing is strictly prohibited.

Operational Limitations & Support Disclaimer:

  • Carrier Filtering: Certain carriers block mobile CLIs to prevent spoofing.

  • No Delivery Guarantees: CM.com cannot guarantee correct CLI display or call completion across all receiving networks.

  • Support Restriction: No SLA guarantees or support can be provided for mobile CLI delivery issues. Use geographic or national fixed numbers for critical business operations.

Can I use a Dutch service number as CLI?

According to the Dutch Telecom Regulator (ACM) the below is allowed to be used as CLI within The Netherlands.

  • “As a number user, you may send any own telephone number prior to a call as long as it matches the destination of the numbering plan, EXCEPT 090x (and 18xy) due to the risk of misuse/ECC Recommendation(11)/02

  • –3190X number users are therefore NOT allowed to send their number with outgoing calls, except for toll-free 090X numbers.

  • –31800 and free 3190X number users are allowed to send their number with an outgoing call, because the risk of consumer damage is nil (free nature).”

Update: ECC Recommendation (11)02 has now been replaced by ECC Recommendation (19)03, recommends “that premium rate numbers should not be presented as OI/CLI”. It is expected that 0800 and free 090x numbers do not qualify as 'premium rate' numbers.