6 Connection types

23.1463GPPRelease 17Technical realization of facsimile Group 3 non-transparentTS

In UMTS, the following connection elements attributes are applicable to these Teleservices.

Connection element: Non-transparent

Duplex Mode: Full Duplex

Synchronous/Asynchronous: Asynchronous

Fixed Network User Rate: 14 400 or 9 600[bit/s]

Wanted Air User Rate: 28 800 or 14 400[bit/s]

Layer 1 and Layer 2 at R reference point are specified in 3GPP TS 27.002, but not here.

To support the ITU-T Recommendation T.30, requiring different transmission rates, the following strategy shall be implemented:

– the channel on the radio interface in UMTS shall be a channel that is satisfied with a user rate of 28 800 bit/s or 14 400 bit/s;

– the transmission rate between the FA and the associated facsimile terminal at both ends shall be the same, i.e. there shall be only one common end‑to‑end transmission rate at any given time;

– the message speed shall be negotiated between T-FAX and R-FAX; this also allows for message speeds of 2 400, 4 800, 7 200, 9 600, or 12 000, 14 400 bit/s to be used;

– the connection between the fax terminals is divided into three logical sections (T-FAX ‑(1)‑ T-FA‑(2)‑ -R-FA-(3)-R-FAX);

– flag stuffing is applied by the FA towards the associated facsimile terminal within the constraints of ITU-T Recommendation T.30, to keep the data link active whenever a procedure delay occurs;

– the BCS protocol elements and the facsimile coded data are buffered at both FAs , if necessary, to guarantee data integrity;

– a specific FA protocol (FA protocol) is provided between both FAs to cater for appropriate link control.

6.1 Protocol model

Figure 4 depicts the protocol stack for this Teleservice.

Depending on the particular implementation, the R reference point may not explicitly exist. In this case, the Layer2 protocol between the FA and the TAF and consequently the Layer2 protocol between the FA and the TAF entities operating across this interface may be omitted. The protocol stack at the radio interface, however, is not affected by this consideration, i.e. RLP and L2RCOP always apply.

All protocol modules specific for this Teleservice shall be confined in the FA functions at both the UE and MSC/IWF ends. The TAF shall comply with the specifications 3GPP TS 27.001 and 3GPP TS 27.002.

Figure 4: Protocol stack for non‑transparent support in UMTS

Figure 5: Communication model

6.2 Mobile to mobile calls

Tandem operation shall be applied to mobile to mobile calls.

6.3 Procedure interrupts

Procedure interrupts shall be supported only in Teleservices 61. In the case of Teleservice 62 any attempt to invoke procedure interrupts by MMI on the MT (see clause 6.4) shall have no effect.

6.4 Radio channel modification

This clause applies to Teleservice 61 only, if a change of the radio channel during the call swapping from speech to facsimile or vice versa is required. For this purpose the in‑call modification procedure (ICM) as detailed in 3GPP TS 24.008 is carried out.

The change from speech to facsimile shall be initiated by MMI at the facsimile terminal starting the ICM procedure via MODIFY signalling.