Question: what does sip stand for in the ngn / ims context
[{'answer': 'Session Initiation Protocol', 'provenance': [{'wikipedia_id': '1152833', 'title': 'IP Multimedia Subsystem', 'start_paragraph_id': 3, 'start_character': 53, 'end_paragraph_id': 3, 'end_character': 80, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1152833', 'title': 'IP Multimedia Subsystem', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 670, 'bleu_score': 0.8851201015398361, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3529648084349251858}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '24701953', 'title': 'SIP provider', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['A SIP provider (Session Initiation Protocol) is any telecommunications company which provides SIP Trunking to customers, usually businesses. Many', 'ing) and "origination"', 'A SIP provider (Session Initiation Protocol) is any telecommunications company which provides SIP Trunking to customers, usually businesses.']}}]}, {'provenance': [{'wikipedia_id': '1152833', 'title': 'IP Multimedia Subsystem', 'section': 'Section::::Abstract.', 'start_paragraph_id': 3, 'end_paragraph_id': 3, 'meta': {'evidence_span': ['IMS uses IETF protocols wherever possible, e.g., the Session Initiation Protocol (SIP). According to the 3GPP,', 'IMS uses IETF protocols wherever possible, e.g., the Session Initiation Protocol (SIP).']}}]}, {'provenance': [{'wikipedia_id': '15371744', 'title': 'Peer-to-peer SIP', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['peer-to-peer (P2P) architecture in which session control between communication end points is facilitated with the Session Initiation Protocol (SIP).', 'Peer-to-peer SIP (P2P-SIP) is an implementation of a distributed voice over Internet Protocol (VoIP) or instant messaging communications application using a peer-to-peer (P2P) architecture in which session control between communication end points is facilitated with the Session Initiation Protocol (SIP).']}}]}]