CONTENTS

�1���� Scope�
�2���� References�
�3���� Definitions��
4���� Abbreviations���
�5���� Introduction������
������� 5.1���� Overview of Text over IP��
������� 5.2���� ToIP system architecture����
������� 5.3���� Compliance requirements���
������� 5.4���� Relationship with other V.15x Recommendations����
�6���� Text telephone-over-IP functions�
�7���� Connection and network scenarios�����������
������� 7.1���� Service and performance requirements for ToIP�����
������� 7.2���� Audio and text functionality
�8���� Transport methods�����������
������� 8.1���� Audio mode����������
������� 8.2���� VBD mode
������� 8.3���� Text relay mode�����
������� 8.4���� Switching between transport modes�����������
�9���� ToIP operational modes���
10���� Text Relay PHY layer operation��
11���� IP transport for text relay
��� ���11.1���� Single and dual port operation of text relay
������ 11.2���� Text relay throughput��������
12���� Support of DTMF in ToIP����������
13���� Transition out of text relay�����������
14���� T.140 encoding of text relay��������
������ 14.1���� Character set support�������
������ 14.2�� ��TIA-825A and T.50 encoding requirements����������
15���� Gateway-to-gateway protocol definitions and procedures
������ 15.1���� Gateway capability and call set-up messages���������
������ 15.2���� Gateway call discrimination messages��������
16���� Start-up mode of operation���������
������ 16.1���� Inter-relationship with V.150.1������
������ 16.2���� Inter-relation with V.152���
17���� Voiceband data modem interworking requirements����������
18���� Facsimile interworking requirements��������
19���� Call set-up procedures����
20���� Call discrimination procedures�����
������ 20.1���� V.8 bis processing
������ 20.2���� V.8 CI/XCI processing�����
������ 20.3���� Call discrimination overview����������
������ 20.4���� Call discrimination SDL diagrams��
������ 20.5���� Visual flow control
Annex A � Procedures for the optional support of SPRT protocol����
������� A.1���� Overview��
������� A.2���� SDP negotiation����
������� A.3���� H.245 negotiation�
Annex B � Definition of capabilities for use within H.245-based systems����
Annex C � SDP description of sessions supporting V.151����
Annex D � Interworking IP text devices with V.151 gateways����
������� D.1���� Introduction����������
������� D.2���� Exchanging capabilities and opening media streams
������� D.3���� State transition and text handling����
Annex E � Payload format and signaling syntax for real-time� text transported within an audio stream����
������� E.1���� Overview��
������� E.2���� Payload format������
������� E.3���� Use of redundancy
Appendix I � Background to PSTN text telephony����
Appendix II � ToIP call discrimination call flows����
������ II.1���� Scope�����
������ II.2���� Scenarios for call discrimination flows���������
������ II.3���� Scenarios with SSE protocol being used�����
������ II.4���� Scenarios with payload type switching being used���
Appendix III � The use of [IETF RFC 2198] in [ITU-T V.151]����
Appendix IV � Text buffering and transmission����
Appendix V � Probing sequence����
Bibliography����