Channel Variables
About
TODO Consolidate with __Channel Variables)
Channel variables are used to manipulate dialplan execution, to control call progress, and to provide options to applications. They play a pervasive role, as FreeSWITCH™ frequently consults channel variables as a way to customize processing prior to a channel's creation, during call progress, and after the channel hangs up.
Click here to expand Table of Contents
- 1 Variable Expansion
- 2 Channel Variables in the XML Dialplan
- 3 Scoped Variables
- 4 Channel Variables in Dial Strings
- 5 Escaping/Redefining Delimiters
- 6 Exporting Channel Variables in Bridge Operations
- 7 Using Channel Variables in Dialplan Condition Statements
- 8 Custom Channel Variables
- 9 Channel Variable Manipulation
- 10 Channel Variable Scope Example
- 11 Accessing Channel Variables in Other Environments
- 12 Info Application Variable Names (variable_xxxx)
Variable Expansion
We rely on variable expansion to create flexible, reusable dialplans:
$${variable}is expanded once when FreeSWITCH™ first parses the configuration on startup or after invokingreloadxml. It is suitable for variables that do not change, such as the domain of a single-tenant FreeSWITCH™ server. That is why$${domain}is referenced so frequently in the vanilla dialplan examples.${variable}is expanded during each pass through the dialplan, so it is used for variables that are expected to change, such as the${destination_number}or${sip_to_user}fields.
Channel Variables in the XML Dialplan
Channel variables are set, appropriately enough, with the set application:
<action application="set" data="var_name=var value"/>
Reading channel variables requires the ${} syntax:
<action application="log" data="INFO The value in the var_name chan var is ${var_name}"/>
<condition field="${var_name}" expression="some text">
Scoped Variables
Channel variables used to be global to the session. As of b2c3199f, it is possible to set variables that only exist within a single application execution and any subsequent applications under it. For example, applications can use scoped variables for named input params:
<action application="log" data="INFO myvar is '${myvar}'"/>
<action application="log" data="%[myvar=Hello]INFO myvar is '${myvar}'"/>
<action application="log" data="INFO myvar is '${myvar}'"/>
<action application="myapp" data="%[var1=val1,var2=val2]mydata"/>
Channel Variables in Dial Strings
The variable assignment syntax for dial strings differs depending on which scope they should apply to:
{foo=bar}is only valid at the beginning of the dial string. It will set the same variables on every channel, but does not do so for enterprise bridging/originate.<foo=bar>is only valid at the beginning of a dial string. It will set the same variables on every channel, including all thos in an enterprise bridging/originate.[foo=bar]goes before each individual dial string and will set the variable values specified for only this channel.
Examples
Set foo variable for all channels implemented and chan=1 will only be set for blah, while chan=2 will only be set for blah2:
{foo=bar}[chan=1]sofia/default/blah@baz.com,[chan=2]sofia/default/blah2@baz.com
Set multiple variables by delimiting with commas:
[var1=abc,var2=def,var3=ghi]sofia/default/blah@baz.com
To have variables in [] override variables in {}, set local_var_clobber=true inside {}. You must also set local_var_clobber=true when you want to override channel variables that have been exported to your b-legs in your dialplan. In this example, the legs for blah1@baz.com and johndoe@example.com would be set to offer SRTP (RTP/SAVP) while janedoe@acme.com would not receive an SRTP offer (she would see RTP/AVP instead):
{local_var_clobber=true,rtp_secure_media=true}sofia/default/blah1@baz.com|sofia/default/johndoe@example.com|rtp_secure_media=false]sofia/default/janedoe@acme.com
Escaping/Redefining Delimiters
Commas are the default delimiter inside variable assignment tags. In some cases (like in absolute_codec_string), we may need to define variables whose values contain literal commas that should not be interpreted as delimiters.
We can redefine the delimiter for a variable using ^^ followed by the desired delimiter:
^^;one,two,three;four,five,six;seven,eight,nine
To set absolute_codec_string=PCMA@8000h@20i@64000b,PCMU@8000h@20i@64000b,G729@8000h@20i@8000b in a dial string:
{absolute_codec_string=^^:PCMA@8000h@20i@64000b:PCMU@8000h@20i@64000b:G729@8000h@20i@8000b,leg_time_out=10,process_cdr=b_only}
This approach does not work when setting sip_h_*, sip_rh_*, and sip_ph headers. To pass a comma into the contents of a private header, escape the comma with a backslash:
{sip_h_X-My-Header=one\,two\,three,leg_time_out=10,process_cdr=b_only}
More information about sip_h_*, **sip_rh_*** variables please check in **Sofia SIP Stack** [Request Headers](/freeswitch/FreeSWITCH-Explained/Configuration/Sofia-SIP-Stack/#adding-request-headers-) and [Response Headers](/freeswitch/FreeSWITCH-Explained/Configuration/Sofia-SIP-Stack/#adding-response-headers-)
Exporting Channel Variables in Bridge Operations
Variables from one call leg (A) can be exported to the other call leg (B) by using the export_vars variable. Its value is a comma separated list of variables that should propagate across calls.
<action application="set" data="export_vars=myvar,myvar2,foo,bar"/>
To set a variable on the A-leg and add it to the export list, use the export application:
<action application="export" data="myvar=true"/>
Using Channel Variables in Dialplan Condition Statements
Channel variables can be used in conditions, refer to XML Dialplan Conditions for more information.
Some channel variables may not be set during the dialplan parsing phrase. See Inline Actions.
Custom Channel Variables
We are not constrained to the channel variables that FreeSWITCH™, its modules, and applications define. It is possible to set any number of unique channel variables for any purpose. They can also be logged in CDR.
The set application can be used to set any channel variable:
<action application="set" data="lead_id=2e4b5966-0aaf-11e8-ba89-0ed5f89f718b"/>
<action application="set" data="campaign_id=333814"/>
<action application="set" data="crm_tags=referral new loyal" />
In a command issued via mod_xml_rpc or mod_event_socket:
originate {lead_id=2e4b5966-0aaf-11e8-ba89-0ed5f89f718,campaign_id=333814}sofia/mydomain.com/18005551212@1.2.3.4 15555551212
Values with spaces must be enclosed by quotes:
originate {crm_tags='referral new loyal'}sofia/mydomain.com/18005551212@1.2.3.4 15555551212
Channel Variable Manipulation
Channel variables can be manipulated for varied results. For example, a channel variable could be trimmed to get the first three digits of a phone number. Manipulating Channel Variables discusses this in detail.
Channel Variable Scope Example
Consider this example:
<extension name="test" continue="false">
<condition field="destination_number" expression="^test([0-9]+)$">
<action application="set" data="fruit=tomato" /> <!-- Set variable in local channel -->
<action application="export" data="veggie=tomato" /> <!-- Set variable in local channel and export it to new channels we bridge to -->
<action application="bridge" data="{meat=tomato}sofia/gateway/testaccount/1234" /><!-- bridge new channel and set variable only in new channel -->
</condition>
</extension>
Leg A (the channel that called the dial plan) will have these variables set:
fruit: tomato
veggie: tomato
Leg B (the channel created with sofia/gateway/testaccount/1234) will have these variables set:
fruit: tomato
meat: tomato
Accessing Channel Variables in Other Environments
In addition to the dialplan, channel variables can be set in other environments as well.
In a FreeSWITCH™ module, written in C:
switch_channel_set_variable(channel,"name","value");
char* result = switch_channel_get_variable(channel,"name");
char* result = switch_channel_get_variable_partner(channel,"name");
In the console (or fs_cli, implemented in mod_commands):
uuid_getvar <uuid> <name>
uuid_setvar <uuid> <name> [<value>]
uuid_setvar_multi <uuid> <name>=<value>[;<name>=<value>[;...]]
Alternatively, call uuid_dump to get all the variables, or use the eval command, adding the prefix variable_ to the key:
uuid_dump <uuid>
eval uuid:<uuid> ${variable_<name>}
In an event socket, just extend the above with the api prefix:
api uuid_getvar <uuid> <name>
In Lua, there are several ways to interact with variables. In the freeswitch.Session() invocation that creates a new Session object, variables go in square brackets:
s = freeswitch.Session("[myname=myvars]sofia/localhost/1003")
With the new Session object s:
local result1 = s:getVariable("myname") -- "myvars"
s:setVariable("name", "value")
local result2 = s:getVariable("name") -- "value"
Info Application Variable Names (variable_xxxx)
Some variables, as shown from the info app, may have variable_ in front of their names. For example, if you pass a header variable called type from the proxy server, it will get displayed as variable_sip_h_type in FreeSWITCH™. To access that variable, you should strip off the variable_, and just do ${sip_h_type}. Other variables shown in the info app are prepended with channel, which should be stripped as well. The example below show a list of info app variables and the corresponding channel variable names:
| Info variable name | channel variable name | Description |
|---|---|---|
| Channel-State | state | Current state of the channel |
| Channel-State-Number | state_number | Integer |
| Channel-Name | channel_name | Channel name |
| Unique-ID | uuid | uuid of this channel's call leg |
| Call-Direction | direction | Inbound or Outbound |
| Answer-State | state | - |
| Channel-Read-Codec-Name | read_codec | the read codec variable mean the source codec |
| Channel-Read-Codec-Rate | read_rate | the source rate |
| Channel-Write-Codec-Name | write_codec | the destination codec same to write_codec if not transcoded |
| Channel-Write-Codec-Rate | write_rate | destination rate same to read rate if not transcoded |
| Caller-Username | username | . |
| Caller-Dialplan | dialplan | user dialplan like xml, lua, enum, lcr |
| Caller-Caller-ID-Name | caller_id_name | . |
| Caller-Caller-ID-Number | caller_id_number | . |
| Caller-ANI | ani | ANI of caller, frequently the same as caller ID number |
| Caller-ANI-II | aniii | ANI II Digits (OLI - Originating Line Information), if available. Refer Here |
| Caller-Network-Addr | network_addr | IP address of calling party |
| Caller-Destination-Number | destination_number | Destination (dialed) number |
| Caller-Unique-ID | uuid | This channel's uuid |
| Caller-Source | source | Source module, i.e. mod_sofia, mod_openzap, etc. |
| Caller-Context | context | Dialplan context |
| Caller-RDNIS | rdnis | Redirected DNIS info. See mod_dptools: transfer application |
| Caller-Channel-Name | channel_name | . |
| Caller-Profile-Index | profile_index | . |
| Caller-Channel-Created-Time | created_time | GMT microseconds timestamp when the channel was created |
| Caller-Channel-Answered-Time | answered_time | GMT microseconds timestamp when the channel was answered |
| Caller-Channel-Hangup-Time | hangup_time | GMT microseconds timestamp when the channel was hung up |
| Caller-Channel-Transfer-Time | transfer_time | GMT microseconds timestamp when the channel was transfered |
| Caller-Screen-Bit | screen_bit | . |
| Caller-Privacy-Hide-Name | privacy_hide_name | . |
| Caller-Privacy-Hide-Number | privacy_hide_number | This variable tells you if the inbound call is asking for CLIR[Calling Line ID presentation Restriction] (either with anonymous method or Privacy:id method) |
| initial_callee_id_name | Sets the callee id name during the 183. This allows the phone to see a name of who they are calling prior to the phone being answered. An example of setting this to the caller id name of the number being dialled: <action application="set" data="initial\_callee\_id\_name='${user\_data(${dialed\_extension}@${domain\_name} var effective\_caller\_id\_name)}'"/> | |
| variable_sip_received_ip | sip_received_ip | . |
| variable_sip_received_port | sip_received_port | . |
| variable_sip_authorized | sip_authorized | . |
| variable_sip_mailbox | sip_mailbox | . |
| variable_sip_auth_username | sip_auth_username | . |
| variable_sip_auth_realm | sip_auth_realm | . |
| variable_mailbox | mailbox | . |
| variable_user_name | user_name | . |
| variable_domain_name | domain_name | . |
| variable_record_stereo | record_stereo | . |
| variable_accountcode | accountcode | Accountcode for the call. This is an arbitrary value. It can be defined in the user variables in the directory, or it can be set/modified from dialplan. The accountcode may be used to force a specific CDR CSV template for the call; if the value of the accountcode variable matches the name of a template then that template will be used. This is valuable for having a specific template be used on a per-call basis. See mod_cdr_csv. |
| variable_user_context | user_context | . |
| variable_effective_caller_id_name | effective_caller_id_name | . |
| variable_effective_caller_id_number | effective_caller_id_number | . |
| variable_caller_domain | caller_domain | . |
| variable_sip_from_user | sip_from_user | . |
| variable_sip_from_uri | sip_from_uri | . |
| variable_sip_from_host | sip_from_host | . |
| variable_sip_from_user_stripped | sip_from_user_stripped | . |
| variable_sip_from_tag | sip_from_tag | . |
| variable_sofia_profile_name | sofia_profile_name | . |
| variable_sofia_profile_domain_name | sofia_profile_domain_name | . |
| variable_sip_full_route | sip_full_route | The complete contents of the Route: header. |
| variable_sip_full_via | sip_full_via | The complete contents of the Via: header. |
| variable_sip_full_from | sip_full_from | The complete contents of the From: header. |
| variable_sip_full_to | sip_full_to | The complete contents of the To: header. |
| variable_sip_req_params | sip_req_params | . |
| variable_sip_req_user | sip_req_user | . |
| variable_sip_req_uri | sip_req_uri | . |
| variable_sip_req_host | sip_req_host | . |
| variable_sip_to_params | sip_to_params | . |
| variable_sip_to_tag | sip_to_tag | . |
| variable_sip_to_user | sip_to_user | . |
| variable_sip_to_uri | sip_to_uri | . |
| variable_sip_to_host | sip_to_host | . |
| variable_sip_contact_params | sip_contact_params | . |
| variable_sip_contact_user | sip_contact_user | . |
| variable_sip_contact_port | sip_contact_port | . |
| variable_sip_contact_uri | sip_contact_uri | . |
| variable_sip_contact_host | sip_contact_host | . |
| variable_sip_invite_domain | sip_invite_domain | . |
| variable_channel_name | channel_name | . |
| variable_sip_call_id | sip_call_id | SIP header Call-ID |
| variable_sip_user_agent | sip_user_agent | . |
| variable_sip_via_host | sip_via_host | . |
| variable_sip_via_port | sip_via_port | . |
| variable_sip_via_rport | sip_via_rport | . |
| variable_presence_id | presence_id | . |
| variable_sip_h_P-Key-Flags | sip_h_p-key-flags | This will contain the optional P-Key-Flags header(s) that may be received from calling endpoint. |
| variable_switch_r_sdp | switch_r_sdp | The whole SDP received from calling endpoint. |
| variable_remote_media_ip | remote_media_ip | . |
| variable_remote_media_port | remote_media_port | . |
| variable_write_codec | write_codec | . |
| variable_write_rate | write_rate | . |
| variable_endpoint_disposition | endpoint_disposition | . |
| variable_dialed_ext | dialed_ext | . |
| variable_transfer_ringback | transfer_ringback | . |
| variable_call_timeout | call_timeout | . |
| variable_hangup_after_bridge | hangup_after_bridge | . |
| variable_continue_on_fail | continue_on_fail | . |
| variable_dialed_user | dialed_user | . |
| variable_dialed_domain | dialed_domain | . |
| variable_sip_redirect_contact_user_0 | sip_redirect_contact_user_0 | . |
| variable_sip_redirect_contact_host_0 | sip_redirect_contact_host_0 | . |
| variable_sip_h_Referred-By | sip_h_referred-by | . |
| variable_sip_refer_to | sip_refer_to | The full SIP URI received from a SIP Refer-To: response |
| variable_max_forwards | max_forwards | . |
| variable_originate_disposition | originate_disposition | . |
| variable_read_codec | read_codec | . |
| variable_read_rate | read_rate | . |
| variable_open | open | . |
| variable_use_profile | use_profile | . |
| variable_current_application | current_application | . |
| variable_ep_codec_string | ep_codec_string | This variable is only available if late negotiation is enabled on the profile. It's a readable string containing all the codecs proposed by the calling endpoint. This can be easily parsed in the dialplan. |
| variable_rtp_disable_hold | rtp_disable_hold | This variable when set will disable the hold feature of the phone. |
| variable_sip_acl_authed_by | sip_acl_authed_by | This variable holds what ACL rule allowed the call. |
| variable_curl_response_data | curl_response_data | This variable stores the output from the last curl made. |
| variable_drop_dtmf | drop_dtmf | Set on a channel to drop DTMF events on the way out. |
| variable_drop_dtmf_masking_file | drop_dtmf_masking_file | If drop_dtmf is true play specified file for every tone received. |
| variable_drop_dtmf_masking_digits | drop_dtmf_masking_digits | If drop_dtmf is true play specified tone for every tone received. |
| sip_codec_negotiation | sip_codec_negotiation | sip_codec_negotiation is basically a channel variable equivalent of inbound-codec-negotiation.sip_codec_negotiation accepts "scrooge" & "greedy" as values.This means you can change codec negotiation on a per call basis. |
| Caller-Callee-ID-Name | - | - |
| Caller-Callee-ID-Number | - | - |
| Caller-Channel-Progress-Media-Time | - | - |
| Caller-Channel-Progress-Time | - | - |
| Caller-Direction | - | - |
| Caller-Profile-Created-Time | profile_created | GMT microseconds timestamp when the caller profile was created |
| Caller-Transfer-Source | - | - |
| Channel-Call-State | - | Current state of the call |
| Channel-Call-UUID | - | - |
| Channel-HIT-Dialplan | - | - |
| Channel-Read-Codec-Bit-Rate | - | - |
| Channel-Write-Codec-Bit-Rate | - | - |
| Core-UUID | - | - |
| Event-Calling-File | - | - |
| Event-Calling-Function | - | - |
| Event-Calling-Line-Number | - | - |
| Event-Date-GMT | - | - |
| Event-Date-Local | - | - |
| Event-Date-Timestamp | - | - |
| Event-Name | - | - |
| Event-Sequence | - | - |
| FreeSWITCH-Hostname | - | - |
| FreeSWITCH-IPv4 | - | - |
| FreeSWITCH-IPv6 | - | - |
| FreeSWITCH-Switchname | - | - |
| Hunt-ANI | - | - |
| Hunt-Callee-ID-Name | - | - |
| Hunt-Callee-ID-Number | - | - |
| Hunt-Caller-ID-Name | - | - |
| Hunt-Caller-ID-Number | - | - |
| Hunt-Channel-Answered-Time | - | - |
| Hunt-Channel-Created-Time | - | - |
| Hunt-Channel-Hangup-Time | - | - |
| Hunt-Channel-Name | - | - |
| Hunt-Channel-Progress-Media-Time | - | - |
| Hunt-Channel-Progress-Time | - | - |
| Hunt-Channel-Transfer-Time | - | - |
| Hunt-Context | - | - |
| Hunt-Destination-Number | - | - |
| Hunt-Dialplan | - | - |
| Hunt-Direction | - | - |
| Hunt-Network-Addr | - | - |
| Hunt-Privacy-Hide-Name | - | - |
| Hunt-Privacy-Hide-Number | - | - |
| Hunt-Profile-Created-Time | profile_created | - |
| Hunt-Profile-Index | - | - |
| Hunt-RDNIS | - | - |
| Hunt-Screen-Bit | - | - |
| Hunt-Source | - | - |
| Hunt-Transfer-Source | - | - |
| Hunt-Unique-ID | - | - |
| Hunt-Username | - | - |
| Presence-Call-Direction | - | - |
| variable_DIALSTATUS | - | - |
| variable_absolute_codec_string | - | - |
| variable_advertised_media_ip | - | - |
| variable_answersec | ||
| variable_answermsec | ||
| variable_answerusec | ||
| variable_billsec | ||
| variable_billmsec | ||
| variable_billusec | ||
| variable_bridge_channel | - | - |
| variable_bridge_hangup_cause | - | - |
| variable_bridge_uuid | - | - |
| variable_call_uuid | - | - |
| variable_current_application_response | - | - |
| variable_direction | - | - |
| variable_duration | ||
| variable_mduration | ||
| variable_uduration | ||
| variable_inherit_codec | - | - |
| variable_is_outbound | - | - |
| variable_last_bridge_to | - | - |
| variable_last_sent_callee_id_name | - | - |
| variable_last_sent_callee_id_number | - | - |
| variable_local_media_ip | - | - |
| variable_local_media_port | - | - |
| variable_number_alias | - | - |
| variable_originate_early_media | - | - |
| variable_originating_leg_uuid | - | - |
| variable_originator | - | - |
| variable_originator_codec | - | - |
| variable_outbound_caller_id_number | - | - |
| variable_progresssec | ||
| variable_progressmsec | ||
| variable_progressusec | ||
| variable_progress_mediasec | ||
| variable_progress_mediamsec | ||
| variable_progress_mediausec | ||
| variable_recovery_profile_name | - | - |
| variable_rtp_audio_in_mos | Mean Opinion Score; read-only, available in CS_REPORTING state, published by CHANNEL_DESTROY event | |
| variable_rtp_use_ssrc | - | - |
| variable_session_id | - | - |
| variable_sip_2833_recv_payload | - | - |
| variable_sip_2833_send_payload | - | - |
| variable_sip_P-Asserted-Identity | - | - |
| variable_sip_Privacy | - | - |
| variable_sip_audio_recv_pt | - | - |
| variable_sip_cid_type | - | - |
| variable_sip_cseq | - | - |
| variable_sip_destination_url | - | - |
| variable_sip_from_display | sip_from_display | 'User' element of SIP From: line |
| variable_sip_from_port | - | - |
| variable_sip_gateway | - | - |
| variable_sip_gateway_name | - | - |
| variable_sip_h_P-Charging-Vector | - | - |
| variable_sip_local_network_addr | - | - |
| variable_sip_local_sdp_str | - | - |
| variable_sip_network_ip | - | - |
| variable_sip_network_port | - | - |
| variable_sip_number_alias | - | - |
| variable_sip_outgoing_contact_uri | - | - |
| variable_sip_ph_P-Charging-Vector | - | - |
| variable_sip_profile_name | - | - |
| variable_sip_recover_contact | - | - |
| variable_sip_recover_via | - | - |
| variable_sip_reply_host | - | - |
| variable_sip_reply_port | - | - |
| variable_sip_req_port | - | - |
| variable_sip_to_port | - | - |
| variable_sip_use_codec_name | - | - |
| variable_sip_use_codec_ptime | - | - |
| variable_sip_use_codec_rate | - | - |
| variable_sip_use_pt | - | - |
| variable_sip_via_protocol | - | - |
| variable_switch_m_sdp | - | - |
| variable_transfer_history | - | - |
| variable_transfer_source | - | - |
| variable_uuid | - | - |
| variable_waitsec | ||
| variable_waitmsec | ||
| variable_waitusec |