Orit Levin. Suppression of Session Initiation Protocol (SIP) REFER Method Implicit Subscription. RFC, 4488:1-8, May 2006. [doi]
@article{rfc4488, title = {Suppression of Session Initiation Protocol (SIP) REFER Method Implicit Subscription}, author = {Orit Levin}, year = {2006}, month = {May}, doi = {10.17487/RFC4488}, url = {https://doi.org/10.17487/RFC4488}, researchr = {https://researchr.org/publication/rfc4488}, cites = {0}, citedby = {0}, journal = {RFC}, volume = {4488}, pages = {1-8}, }