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| Chapter 9 Voice |
| Table 58 VoIP > SIP > SIP Service Provider (continued) | |
| LABEL | DESCRIPTION |
| SRTP Support | When you make a VoIP call using SIP, the |
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| (RTP) is used to handle voice data transfer. The Secure |
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| Transport Protocol (SRTP) is a security profile of RTP. It is designed to |
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| provide encryption and authentication for the RTP data in both unicast |
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| and multicast applications. |
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| SRTP uses the Advanced Encryption Standard (AES) cipher for data |
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| encryption. The |
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| Authentication Code (HMAC) calculation with Secure Hash Algorithm |
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| authentication tag that is appended to the packet. |
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| Both the caller and callee should use the same algorithms to establish |
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| an SRTP session. |
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| SRTP Support | Select this option to enable SRTP on the |
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| Crypto Suite | Select the encryption and authentication algorithm set used by the P- |
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| Select AES_CM_128_HMAC_SHA1_80 or |
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| AES_CM_128_HMAC_SHA1_32 to enable both data encryption and |
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| authentication for voice data. |
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| Select AES_CM_128_NULL to use |
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| data authentication. |
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| Select NULL_CIPHER_HMAC_SHA1_80 to disable encryption but |
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| require authentication using the default |
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| DTMF Mode |
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| DTMF Mode | Control how the |
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| makes when you push its buttons. You should use the same mode your |
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| VoIP service provider uses. |
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| RFC2833 - send the DTMF tones in RTP packets. |
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| InBand - send the DTMF tones in the voice data stream. This method |
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| works best when you are using a codec that does not use compression |
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| (like G.711). Codecs that use compression (like G.729 and G.726) can |
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| distort the tones. |
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| SIPInfo - send the DTMF tones in SIP messages. |
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| Transport Type |
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| Transport Type | Select the transport layer protocol (TCP, UDP or TLS) used for SIP. |
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| AUTO is available when you select the Support Locating SIP Server |
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| option. If you select AUTO here, the |
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| Name Authority Pointer (NAPTR) query to locate the SIP server and get |
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| the supported transport layer protocol(s). |
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| FAX Option | This field controls how the |
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| G.711 Fax | Select this if the |
| Passthrough | messages. The peer devices must also use G.711. |
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| 207 |
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