annot contact the telephony application server. The field "service information" contains data which are transparent for the HSS and S-CSCF entities. These data are handled only by the telephony application server. 5.2. VoLTE profile service 5.2.1. Supplementary telephone services The user agent (UA) indicates that it supports supplementary telephone service by adding in the REGISTER and INVITE requests, the parameter g.3gpp.icsi-ref associated with the header Contact. Contact: <sip:192.0.2.101>;expires=600000;+g.3gpp. .icsi- ef="urn:urn-7:3A3gpp-service-ims.icsi.mmtel" - Table 5.1 lists the supplementary telephone service. The shaded boxes represent supplementary telephone service described in this chapter. 5.2.1.1. Communication diversion CDIV consists of diverting a call (from Alice to Bob) to a different destination (Carol). In this scenario, CDIV is implemented by the telephony application server associated with the callee's (i.e. Bob's) S-CSCF entity. Service Profiles (Communication DIVersion) (Originating Identification Presentation) (Originating Identification Restriction) (Terminating Identification Presentation) (Terminating Identification Restriction) (Message Waiting Indication) (Communication hold) (CONFerence calling) (Communication Waiting) (Communication Barring) (Explicit Communication Transfer) (Malicious Communication Identification) (Completion of Communications to Busy Subscriber) (Completion of Communications on No Reply) (Advice Of Charge) (Closed User Group) (Customised Alerting Tone) (Customised Ringing Signal) (Flexible Alerting) Table 5.1. Supplementary telephone service 152 VoLTE and ViLTE 5.2.1.1.1. CFU Communication forwarding unconditional (CFU) consists systematically forwarding an incoming call to another destination. However, the outgoing calls initiated by Bob's UA entity are not affected by this service. Optionally, a subscription service may be offered to Bob, giving him an indication that CFU is active. This information is transmitted to him when Bob initializes a communicatio