XCAP Supplementary Services (Simservs)

OmniSEP implements ETSI TS 183 023 XCAP (XML Configuration Access Protocol) for managing IMS supplementary services including call forwarding, call barring, and caller ID settings.

Control Panel UI

The XCAP Simservs Profiles page provides a web-based interface for viewing and managing subscriber profiles:

Features:

• Search and filter local profiles by MSISDN
• Fetch profiles from HSS using Diameter Sh interface
• View profile details in a 2-column layout:
  • Left column: Identity Services (OIP/OIR), Other Services (Call Waiting, Call Hold), Call Forwarding rules
  • Right column: Incoming and Outgoing Call Barring rules with conditions
• Push/Pull synchronization with HSS
• Edit mode for modifying profile settings

Overview

Simservs Document Structure

The simservs document follows ETSI TS 183 023 structure:

HTTP Interface

XCAP URL Format

/simservs.ngn.etsi.org/users/{sip_uri}/simservs.xml[/~~/{xpath}]

Component	Description	Example
{sip_uri}	SIP URI with MSISDN	sip:+15551234567@ims.example.com
{xpath}	XPath selector (optional)	simservs/communication-diversion

Operations

Method	Path	Description
GET	/simservs.ngn.etsi.org/users/{sip}/simservs.xml	Get full document
PUT	/simservs.ngn.etsi.org/users/{sip}/simservs.xml	Replace full document
GET	/simservs.ngn.etsi.org/users/{sip}/simservs.xml/~~/simservs/{service}	Get service element
PUT	/simservs.ngn.etsi.org/users/{sip}/simservs.xml/~~/simservs/{service}	Update service element
DELETE	/simservs.ngn.etsi.org/users/{sip}/simservs.xml/~~/simservs/{service}/{element}	Delete element

Content Types

Content-Type	Usage
application/xcap-el+xml	XCAP element operations
application/xml	Standard XML

ETag Support

OmniSEP implements RFC 4825 ETag-based concurrency control:

Header	Usage
ETag	Response header with document version
If-Match	Conditional update (PUT/DELETE)
If-None-Match	Conditional GET (304 Not Modified)

Caching Architecture

OmniSEP uses a local-first caching strategy with ETS-based storage and asynchronous HSS synchronization.

Storage Tables

Table	Key	Value	Purpose
xcap_profiles	IMSI	{profile_map, etag}	Primary profile storage
xcap_by_msisdn	MSISDN	IMSI	Lookup index for XCAP requests

Caching Strategy

Read Operations (GET)

1. Query local ETS cache first
2. On cache miss, fetch from HSS via Diameter Sh
3. Seed local cache with HSS response
4. Return default profile if HSS unavailable or no profile exists

Write Operations (PUT)

1. Validate ETag precondition against cached value
2. Update local cache immediately
3. Return response to client with new ETag
4. Asynchronously push changes to HSS (non-blocking)

ETag Generation

ETags are computed as MD5 hashes of the profile data:

ETag = MD5(erlang:term_to_binary(profile))[0:16]

Example: "a1b2c3d4e5f6g7h8"

The 16-character hex string changes whenever any profile field is modified, enabling precise cache invalidation.

Concurrency Control

Mechanism	Purpose
ETS read_concurrency	Fast parallel reads without locking
GenServer writes	Atomic write operations
ETag validation	Prevents lost updates from concurrent clients

Default Profile

Unknown subscribers automatically receive a default profile per 3GPP TS 24.623:

• All supplementary services active
• OIR default: presentation-not-restricted
• NoReplyTimer: 20 seconds
• Empty call forwarding/barring rulesets

This ensures devices always receive a valid response without requiring pre-provisioning.

HSS Integration

Operation	Diameter Command	Timing
Fetch profile	Sh UDR (User-Data-Request)	Synchronous on cache miss
Push changes	Sh PUR (Profile-Update-Request)	Asynchronous after PUT

The asynchronous push means HSS updates don't block client responses, improving latency for device requests.

Simservs XML Document

Full Document Example

<?xml version="1.0" encoding="UTF-8"?>
<simservs xmlns="http://uri.etsi.org/ngn/params/xml/simservs/xcap"
          xmlns:cp="urn:ietf:params:xml:ns:common-policy">

  <originating-identity-presentation active="true"/>

  <originating-identity-presentation-restriction active="true">
    <default-behaviour>presentation-not-restricted</default-behaviour>
  </originating-identity-presentation-restriction>

  <communication-diversion active="true">
    <NoReplyTimer>20</NoReplyTimer>
    <cp:ruleset>
      <cp:rule id="cfb">
        <cp:conditions>
          <busy/>
        </cp:conditions>
        <cp:actions>
          <forward-to>
            <target>tel:+15557654321</target>
            <notify-caller>false</notify-caller>
          </forward-to>
        </cp:actions>
      </cp:rule>
    </cp:ruleset>
  </communication-diversion>

  <incoming-communication-barring active="false">
    <cp:ruleset/>
  </incoming-communication-barring>

  <outgoing-communication-barring active="false">
    <cp:ruleset/>
  </outgoing-communication-barring>

</simservs>

Namespaces

Prefix	Namespace	Description
(default)	http://uri.etsi.org/ngn/params/xml/simservs/xcap	ETSI Simservs
cp	urn:ietf:params:xml:ns:common-policy	RFC 4745 Common Policy

Services

Originating Identity Presentation (OIP)

Controls whether caller ID is displayed to called party.

<originating-identity-presentation active="true"/>

Attribute	Type	Description
active	Boolean	Service enabled/disabled

Originating Identity Presentation Restriction (OIR)

Controls caller ID hiding.

<originating-identity-presentation-restriction active="true">
  <default-behaviour>presentation-not-restricted</default-behaviour>
</originating-identity-presentation-restriction>

Element	Values	Description
default-behaviour	presentation-restricted, presentation-not-restricted	Default caller ID behavior

Communication Diversion (Call Forwarding)

Rule Types

Rule ID	Condition	Description
cfu	(none)	Call Forwarding Unconditional - forwards all calls immediately
cfb	busy	Call Forwarding on Busy
cfna	no-answer	Call Forwarding on No Answer (uses NoReplyTimer)
cfnrc	not-reachable	Call Forwarding on Not Reachable
cfnl	not-logged-in	Call Forwarding on Not Logged In

Call Forwarding Rule Structure

<communication-diversion active="true">
  <NoReplyTimer>20</NoReplyTimer>
  <cp:ruleset>
    <cp:rule id="cfna">
      <cp:conditions>
        <no-answer/>
      </cp:conditions>
      <cp:actions>
        <forward-to>
          <target>tel:+15557654321</target>
          <notify-caller>false</notify-caller>
        </forward-to>
      </cp:actions>
    </cp:rule>
  </cp:ruleset>
</communication-diversion>

Element	Type	Description
NoReplyTimer	Integer	Seconds to wait before CFNA (1-300)
cp:rule/@id	String	Rule identifier (cfu, cfb, cfna, cfnrc, cfnl)
target	tel: URI	Forward destination number
notify-caller	Boolean	Play announcement to caller

Target URI Format

Forward targets use tel: URI format per RFC 3966:

tel:+15557654321;phone-context=ims.mnc001.mcc310.3gppnetwork.org

Component	Description
tel:	URI scheme
+15557654321	E.164 number with country code
phone-context	IMS domain (optional)

Call Barring

Incoming Communication Barring

<incoming-communication-barring active="true">
  <cp:ruleset>
    <cp:rule id="international">
      <cp:conditions>
        <international/>
      </cp:conditions>
      <cp:actions>
        <allow>false</allow>
      </cp:actions>
    </cp:rule>
  </cp:ruleset>
</incoming-communication-barring>

Outgoing Communication Barring

<outgoing-communication-barring active="true">
  <cp:ruleset>
    <cp:rule id="international">
      <cp:conditions>
        <international/>
      </cp:conditions>
      <cp:actions>
        <allow>false</allow>
      </cp:actions>
    </cp:rule>
  </cp:ruleset>
</outgoing-communication-barring>

Barring Rule Types

Rule ID	Condition	Description
all	(none)	Bar all calls
international	international	Bar international calls
international-exHC	international-exHC	Bar international except home country
roaming	roaming	Bar calls while roaming

API Examples

Get Full Simservs Document

GET /simservs.ngn.etsi.org/users/sip:+15551234567@ims.example.com/simservs.xml
Accept: application/xcap-el+xml

Response:

HTTP/1.1 200 OK
Content-Type: application/xcap-el+xml
ETag: "a1b2c3d4e5f6g7h8"

<?xml version="1.0" encoding="UTF-8"?>
<simservs xmlns="http://uri.etsi.org/ngn/params/xml/simservs/xcap"...>
  ...
</simservs>

Get Call Forwarding Settings

GET /simservs.ngn.etsi.org/users/sip:+15551234567@ims.example.com/simservs.xml/~~/simservs/communication-diversion

Enable Call Forwarding on Busy

PUT /simservs.ngn.etsi.org/users/sip:+15551234567@ims.example.com/simservs.xml/~~/simservs/communication-diversion/cp:ruleset/cfb
Content-Type: application/xcap-el+xml
If-Match: "a1b2c3d4e5f6g7h8"

<cp:rule id="cfb">
  <cp:conditions>
    <busy/>
  </cp:conditions>
  <cp:actions>
    <forward-to>
      <target>tel:+15557654321</target>
      <notify-caller>false</notify-caller>
    </forward-to>
  </cp:actions>
</cp:rule>

Disable Call Forwarding Rule

DELETE /simservs.ngn.etsi.org/users/sip:+15551234567@ims.example.com/simservs.xml/~~/simservs/communication-diversion/cp:ruleset/cfb
If-Match: "a1b2c3d4e5f6g7h8"

Update NoReplyTimer

PUT /simservs.ngn.etsi.org/users/sip:+15551234567@ims.example.com/simservs.xml/~~/simservs/communication-diversion/NoReplyTimer
Content-Type: application/xcap-el+xml

25

Management API

For administrative access, use the JSON management API:

Get Profile

GET /api/xcap/15551234567

Response:

{
  "oip": { "active": true },
  "oir": {
    "active": true,
    "default_behaviour": "presentation-not-restricted"
  },
  "no_reply_timer": 20,
  "call_forwarding": {
    "cfb": {
      "enabled": true,
      "target": "tel:+15557654321",
      "condition": "busy"
    }
  },
  "call_barring_incoming": {},
  "call_barring_outgoing": {}
}

Set Profile

POST /api/xcap/15551234567
Content-Type: application/json

{
  "no_reply_timer": 25,
  "call_forwarding": {
    "cfna": {
      "enabled": true,
      "target": "tel:+15559876543",
      "condition": "no-answer"
    }
  }
}

Default Profile

New subscribers receive this default profile:

Setting	Default
OIP	Active
OIR	Active, presentation-not-restricted
NoReplyTimer	20 seconds
Call Forwarding	All rules disabled
Call Barring (Incoming)	All calls allowed
Call Barring (Outgoing)	All calls allowed

Error Responses

HTTP Status	Description
200	Success
304	Not Modified (If-None-Match matched)
400	Bad Request - Invalid XML or path
404	Not Found - Document or element not found
405	Method Not Allowed
409	Conflict - Constraint violation
412	Precondition Failed - ETag mismatch

Error Response Format

<?xml version="1.0" encoding="UTF-8"?>
<xcap-error xmlns="urn:ietf:params:xml:ns:xcap-error">
  <error-element>Element not found: simservs/unknown</error-element>
</xcap-error>

Reference Specifications

Specification	Description
ETSI TS 183 023	XCAP framework for NGN Simservs
ETSI TS 183 004	Communication Diversion (CDIV)
RFC 4825	XCAP Protocol
RFC 4745	Common Policy
RFC 3966	tel: URI
3GPP TS 24.623	XCAP over Ut interface