How to configure Caller ID
From SIPfoundry sipx, The Open Source SIP PBX for Linux - Calivia
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How to configure Caller ID
sipX release 3.6 adds a very flexible mechanism to configure Caller ID (CLID). Caller ID can be defined per user, on a user group level, or per gateway. Different rules apply of which setting takes precedent. In addition, Caller ID can be derived from the user ID where it is possible, on a per gateway basis, to strip leading digits and add a new prefix. This allows different Caller ID to be transmitted for the same user dependent which gateway the call is routed through. I.e. a call to London through the London gateway would include a different CLID as compared to a call to Los Angeles through the local gateway there.
Caller ID can also be blocked on a per user or per gateway basis (CLIR). Below are some of the details.
Caller ID defined for the User or the User Group
The objective is to allow for maximum flexibility selecting the following important parameters on a per user basis: 1) The User ID, which is what the phone displays as the line ID, 2) The internal extension number or name, 3) The Direct Inbound Dialing (DID) number, and 4) Caller ID. With the current implementation, all these parameters can be selected independently with a great deal of user control.
Typically the best way of doing this is as follows:
- Select the real name of the user as the User ID. This means that on the phone display (your own as well as on the attendant console of a receptionist or operator), your real name will appear. That makes it easy to remember.
- Assign a numeric extension as an alias for internal dialing
- Assign a numeric alias for the user's DID number as it is forwarded from the gateway for incoming calls for users who have a DID
- Assign Caller ID to represent the DID number for outgoing calls for users who have DID. For users who do not have DID you could let the gateway assign a default Caller ID that represents the company number
Caller ID can also be defined at the User Group level. This will mean that a group of users will share the same caller ID number for outgoing calls. This could be helpful if these users are e.g. in a hunt group and incoming calls to this one number will be answered by who is available. Caller ID group settings are overwritten by settings for individual users. If the user is in several groups, the setting of the last group counts.
Caller ID defined on the Gateway
Defining Caller ID properties on the gateway is a very powerful mechanism that allows a lot of flexibility. It is possible to define a gateway default caller ID that can either overwrite user caller ID settings or only apply to users who do not have caller ID defined. If user caller ID is to be considered, it is possible to strip digits and add a new prefix to the number received from the user. The result can be specific caller ID dependent on the gateway used to route the call. E.g. if you are a sales rep and have customers in different countries, then you could send a local caller ID for your customers to use to call you back. The only condition for this to work is that the last n digits of the number remain the same for all gateways.
Implementation details
Caller ID manipulation is implemented by sipXproxy, which modifies 'From' field for outgoing calls according to the rules specified in caller-alias dataset. sipXconfig is responsible for preparin caller-aliases based on administrator input. Blocking caller id is achieved by inserting 'sip:anonymous@anonymous.invalid' contact into From field. The value of the anonymous contact can be changed by adding 'caller-aliasDataSet.anonymousAlias' property in the sipxconfig.properties.in configuration file. For example:
caller-aliasDataSet.anonymousAlias=sip:nobody@example.com
