https://community.sinch.com/t5/Elastic-SIP-Trunking/Are-Sinch-Elastic-SIP-Trunks-603-compliant/ta-p/19728 <DIV class="lia-message-template-content-zone"> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-olk-copy-source="MessageBody" data-ogsc="rgb(0, 0, 0)">Sinch Elastic SIP Trunks are 603+ compliant. If you send a call which is blocked by the far end network they may return a "603 Network Blocked" message. &nbsp;Contained within this message will be a reason explaining why the blocking occurred and often a URL or resource which can be followed to request that the block be removed.&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)"><STRONG>Example of a 603 Network Blocked response.&nbsp;</STRONG></DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)"><LI-CODE lang="markup">Reason: SIP;cause=603;text="v=analytics1;url=https://www.t-mobile.com/responsibility/consumer-info/additional-info/call-blocking-redress";location=RLN</LI-CODE></DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">It should be noted that while the regulations refer to this as "603+” there is no actual “+” sign sent in the SIP messaging.&nbsp;</DIV> </DIV> Fri, 10 Jul 2026 15:01:27 GMT Alex_Sberna 2026-07-10T15:01:27Z https://community.sinch.com/t5/Elastic-SIP-Trunking/Are-Sinch-Elastic-SIP-Trunks-603-compliant/ta-p/19728 <DIV class="lia-message-template-content-zone"> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-olk-copy-source="MessageBody" data-ogsc="rgb(0, 0, 0)">Sinch Elastic SIP Trunks are 603+ compliant. If you send a call which is blocked by the far end network they may return a "603 Network Blocked" message. &nbsp;Contained within this message will be a reason explaining why the blocking occurred and often a URL or resource which can be followed to request that the block be removed.&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)"><STRONG>Example of a 603 Network Blocked response.&nbsp;</STRONG></DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)"><LI-CODE lang="markup">Reason: SIP;cause=603;text="v=analytics1;url=https://www.t-mobile.com/responsibility/consumer-info/additional-info/call-blocking-redress";location=RLN</LI-CODE></DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">&nbsp;</DIV> <DIV style="border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-variant-alternates: inherit; font-variant-position: inherit; font-variant-emoji: inherit; font-weight: 400; font-stretch: inherit; font-size: 12pt; line-height: inherit; font-family: '&amp;quot;Aptos&amp;quot;', Arial, Helvetica, sans-serif; font-optical-sizing: inherit; font-size-adjust: inherit; font-kerning: inherit; font-feature-settings: inherit; font-variation-settings: inherit; font-language-override: inherit; margin: 0px; padding: 0px; vertical-align: baseline; color: #000000 !important; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; direction: ltr;" data-ogsc="rgb(0, 0, 0)">It should be noted that while the regulations refer to this as "603+” there is no actual “+” sign sent in the SIP messaging.&nbsp;</DIV> </DIV> Fri, 10 Jul 2026 15:01:27 GMT https://community.sinch.com/t5/Elastic-SIP-Trunking/Are-Sinch-Elastic-SIP-Trunks-603-compliant/ta-p/19728 Alex_Sberna 2026-07-10T15:01:27Z