Caller ID is Key to Effective Call Delivery 

Spam calls have become such a widespread nuisance, that strict Caller ID enforcement has become part of the daily workflow for Telecom. 

CallnFax offers two options for managing your Caller ID when using our A-Z Termination feature. Option number 1 is to set a static Caller ID in your SIP Trunk profile. This is the recommended method, as it is the most reliable one. The static Caller ID is set in E164 format (+XXX XXX NNNN) and is sent along with your outbound call. 

In Caller ID option number 2, we send along the Caller ID that you send us. This is useful when you need to support multiple Caller ID’s. CallnFax will propagate your Caller ID header, supporting Call Centers with multiple DID’s. The advantage of option 2 is the flexibility of supporting any Caller ID that you have legal right to display. All DID’s from CallnFax are valid (no grey routes) and legal and can be registered with any calling authority (discussed in article 2). 

The disadvantage of calling option 2, is if your Caller ID header is not E164 compliant, there is a good chance that your call will fail. 

Testing for correct Caller ID when terminating calls is usually accomplished through a series of test calls. Test calls should be performed on both mobile, and landline numbers, preferably from local, national, and international routes. Thorough testing is not always possible, but testing internationally is recommended.

E164 formatting is probably familiar to everyone. When your mobile rings and the Caller ID reads as “+ XXX XXX NNNN”, this is E164 compliance. Your SIP Trunk header contains this information, and it needs to be correctly formatted to function correctly.

This is a general guide, for your reference:

E.164 phone number format contains:

[+][country code][area code][local phone number]

• + – plus sign
• country code – international country code
• area code/national destination code – code without leading 0
• phone number – local phone number