Henning Schulzrinne. A SIP Response Code for Unwanted Calls. RFC, 8197:1-8, July 2017. [doi]
@article{rfc8197, title = {A SIP Response Code for Unwanted Calls}, author = {Henning Schulzrinne}, year = {2017}, month = {July}, doi = {10.17487/RFC8197}, url = {https://doi.org/10.17487/RFC8197}, researchr = {https://researchr.org/publication/rfc8197}, cites = {0}, citedby = {0}, journal = {RFC}, volume = {8197}, pages = {1-8}, }