- Cisco Employee,
There may be scenarios where a third party vendor’s PBX hardware uses a proprietary ISDN signaling protocol. Unless the same PBX (signaling standard) is used on both ends of the circuit, you need a way so that the two PBXs or voice gateways can properly communicate signaling information back and forth. QSIG is an open standard protocol which defines services and signaling protocols for Private Integrated Services Networks (PISNs) to overcome this issue. It is a peer-to-peer signaling protocol that uses Q.931 as its underlying signaling protocol but modifies the signals so proprietary ISDN signaling protocols can be used by non-proprietary equipment on the other end of the connection.
The ISDN Q.921 and Q.931 standards provide the basis for QSIG protocol, which sets a worldwide standard for PBX interconnection. In a basic QSIG call, a user in a Private Integrated Services Network Exchange (PINX) can place a call to a user that is in a remote PINX. The called party receives the caller name or number as the call rings. The calling party receives the called name and number when the user phone rings in the remote PINX. All the features that are available as a PBX user operate transparently across the network. QSIG protocol provides supplementary and additional network features, as defined for PISNs, if the corresponding set of QSIG features are supported by both ends of the call.
Cisco UC solutions support QSIG to connect with various vendors’ PBX systems and Central Office (CO) switches that use the QSIG standard. Note that if QSIG information is being tunneled to CUCM (or if it is a MGCP PRI to CUCM running QSIG) then the feature set supported will differ from that which is supported in IOS.
The switch type confiugred must be QSIG:
isdn switch-type primary-qsig
To have IOS decode QSIG messages, enable:
voice service voip qsig decode
To enable Call Diversion:
interface Serial x/y/z:23 isdn supp-service calldiversion
For Transparent Tunneling of QSIG and Q.931 over SIP/H.323:
voice service voip signaling forward unconditional OR signaling forward rawmsg !this command can also be placed under the respective VoIP dial-peer
For translation between SIP and QSIG MWI, only unsolicited notify is supported:
sip-ua mwi-server dns:cisco.com expires 60 port 5060 transport udp unsolicitedvoice service voip
For CME with QSIG PBX:
voice service voip qsig decode voice service pots supplementary-service qsig call-forward
For CME with QSIG PBX being used as Voicemail Server such as Mitel:
voice service voip qsig decode telephony-service voicemail <number> ephone-dn <tag> mwi qsig dial-peer voice <tag> pots destination-pattern <voicemail-number> port x/y/z:23
H.450.7 may need to be enabled for some scenarios where transferring via Q.SIG over H323:
voice service voip supplementary-service h450.7
CUCM supports both ECMA and ISO standards for Q.SIG. See the endpoint specific configuration in CUCM to ensure that it is provisioned properly. There are also sevral QSIG service parameters in CUCM under varios sections such as call forward.
QSIG Support on IOS Voice GWs
Please refer the link below:
Please reference the QSIG section in the CME Admin guide for the latest information: