The X-Msw-Companion-Device header is a custom SIP header used by Sentinel VoLTE when a companion device may be used on a call.

The terminating MMTel-AS instance inserts this header in the initial INVITE if the served user’s Metaswitch-TAS-Services transparent data indicates that they have a companion device. If the subscriber has multiple companion devices, multiple header values will be inserted. The header conveys this information to the terminating SCC-AS instance. The T-ADS features in the SCC-AS will use this information to decide whether the INVITE should be forked to the companion device.

Note

  • The header is for internal use only and is automatically removed when the INVITE exits the terminating SCC-AS instance.

  • The header will also be removed at the MMTel-AS if retargeting has occurred.

Header Format

The header name is X-Msw-Companion-Device, and its value is the companion device information provisioned for the subscriber. The header is presented in the following format:

X-Msw-Companion-Device: <radioAccessType>[;<parameters>]

<radioAccessType> is either CS, PS, or PS-CS, where PS value indicates the subscriber has a companion device supporting packet-switched radio access types, e.g. LTE or WiFi. CS value indicates the companion device supports 3G network.

The <parameters> are normal SIP name=value header parameters which can include common parameters and CS only parameters.

Common Parameters

Parameter Description Example Mandatory or Optional

model

quoted-string containing the companion model

model="CompanionWatch"

Optional

impi

quoted-string containing an IMPI (23.003 §13.3)

impi="234150999999999@ims.mnc015.mcc234.3gppnetwork.org"

Optional

imsi

quoted-string containing an IMSI (23.003 §2.2)

imsi="234150999999999"

Optional

imei

quoted-string containing an IMEI (23.003 §13.13)

imei="sip:90420156-025763-0@ims.mnc015.mcc234.3gppnetwork.org"

Optional

CS Only Parameters

Parameter Description Example Mandatory or Optional

msisdn

quoted-string containing an MSISDN

msisdn="1234567"

Mandatory

Example:

  • For PS companion device:

    X-Msw-Companion-Device: PS;model="CompanionWatch"

  • For CS companion device with optional parameters:

    X-Msw-Companion-Device: CS;model="CompanionGlass";msisdn="1234567";imei="sip:90420156-025763-0@ims.mnc015.mcc234.3gppnetwork.org"

  • For multiple devices:

    X-Msw-Companion-Device: PS-CS;model="CompanionWatch";msisdn="1234567";imei="sip:90420156-025763-0@ims.mnc015.mcc234.3gppnetwork.org
X-Msw-Companion-Device: CS;model="CompanionGlass";msisdn="1234568"

Header Usage

The header is set by Set Companion Device Headers feature.

The header is decoded by SCC Decode Companion Device Info feature.

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Sentinel VoLTE Version 4.0.0