我有一个星号框，我已成功设置在路由器后面，可以在网络内启动呼叫，即使它们是通过VoIP提供商到外部网络没有问题。
问题摘要：
我认为问题存在于校验和中我不知道为什么只有当网络外的呼叫开始时才会发生。
以下是从客户端发送到星号的错误数据包，下面是一个很好的数据包。您可以看到“标头校验和”和“标志”不同。我相信我的路由器阻止了这些。需要知道这个问题的原因/解决方案。
错误的RTP数据包（互联网协议下的问题 - ＆gt;标头校验和）：
Frame 367: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Interface id: 0
Encapsulation type: Ethernet (1)
Arrival Time: Jul 12, 2013 18:17:09.531568000 Central America Standard Time
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1373674629.531568000 seconds
[Time delta from previous captured frame: 0.019850000 seconds]
[Time delta from previous displayed frame: 0.019850000 seconds]
[Time since reference or first frame: 35.709907000 seconds]
Frame Number: 367
Frame Length: 74 bytes (592 bits)
Capture Length: 74 bytes (592 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:udp:rtp]
[Number of per-protocol-data: 1]
[Real-Time Transport Protocol, key 0]
[Coloring Rule Name: Checksum Errors]
[Coloring Rule String: eth.fcs_bad==1 || ip.checksum_bad==1 || tcp.checksum_bad==1 || udp.checksum_bad==1 || sctp.checksum_bad==1 || mstp.checksum_bad==1 || cdp.checksum_bad==1 || edp.checksum_bad==1 || wlan.fcs_bad==1]
Ethernet II, Src: Sony_ed:dd:f7 (30:f9:ed:ed:dd:f7), Dst: Cisco_15:ae:21 (00:23:33:15:ae:21)
Destination: Cisco_15:ae:21 (00:23:33:15:ae:21)
Address: Cisco_15:ae:21 (00:23:33:15:ae:21)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: Sony_ed:dd:f7 (30:f9:ed:ed:dd:f7)
Address: Sony_ed:dd:f7 (30:f9:ed:ed:dd:f7)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IP (0x0800)
Internet Protocol Version 4, Src: 172.17.16.1 (172.17.16.1), Dst: 190.86.xxx.xxx (190.86.xxx.xxx)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 60
Identification: 0x5acd (23245)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: UDP (17)
Header checksum: 0x0000 [incorrect, should be 0x7406 (may be caused by "IP checksum offload"?)]
[Good: False]
[Bad: True]
[Expert Info (Error/Checksum): Bad checksum]
[Message: Bad checksum]
[Severity level: Error]
[Group: Checksum]
Source: 172.17.16.1 (172.17.16.1)
Destination: 190.86.xxx.xxx (190.86.xxx.xxx)
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 61448 (61448), Dst Port: 18668 (18668)
Source port: 61448 (61448)
Destination port: 18668 (18668)
Length: 40
Checksum: 0x2c17 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
Real-Time Transport Protocol
[Stream setup by SDP (frame 363)]
[Setup frame: 363]
[Setup Method: SDP]
10.. .... = Version: RFC 1889 Version (2)
..0. .... = Padding: False
...0 .... = Extension: False
.... 0000 = Contributing source identifiers count: 0
0... .... = Marker: False
Payload type: ITU-T G.729 (18)
Sequence number: 2
[Extended sequence number: 65538]
Timestamp: 2785685929
Synchronization Source identifier: 0x2627735d (640119645)
Payload: f3f1c5244e9ac20007d6d5bf48c87ea58f774bad
Header Checksum很好的好包
Frame 1350: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Interface id: 0
Encapsulation type: Ethernet (1)
Arrival Time: Jul 13, 2013 11:52:41.927873000 Central America Standard Time
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1373737961.927873000 seconds
[Time delta from previous captured frame: 0.001024000 seconds]
[Time delta from previous displayed frame: 0.021851000 seconds]
[Time since reference or first frame: 36.468877000 seconds]
Frame Number: 1350
Frame Length: 74 bytes (592 bits)
Capture Length: 74 bytes (592 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ip:udp:rtp]
[Number of per-protocol-data: 1]
[Real-Time Transport Protocol, key 0]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]
Ethernet II, Src: IntelCor_33:71:4c (c4:85:08:33:71:4c), Dst: IntelCor_0b:6a:85 (68:05:ca:0b:6a:85)
Destination: IntelCor_0b:6a:85 (68:05:ca:0b:6a:85)
Address: IntelCor_0b:6a:85 (68:05:ca:0b:6a:85)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: IntelCor_33:71:4c (c4:85:08:33:71:4c)
Address: IntelCor_33:71:4c (c4:85:08:33:71:4c)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IP (0x0800)
Internet Protocol Version 4, Src: 192.168.77.94 (192.168.77.94), Dst: 190.86.xxx.xxx (190.86.xxx.xxx)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport))
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00)
Total Length: 60
Identification: 0x6c79 (27769)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: UDP (17)
Header checksum: 0x5066 [correct]
[Good: True]
[Bad: False]
Source: 192.168.77.94 (192.168.77.94)
Destination: 190.86.xxx.xxx (190.86.xxx.xxx)
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 49722 (49722), Dst Port: 12886 (12886)
Source port: 49722 (49722)
Destination port: 12886 (12886)
Length: 40
Checksum: 0xaa67 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
Real-Time Transport Protocol
[Stream setup by SDP (frame 480)]
[Setup frame: 480]
[Setup Method: SDP]
10.. .... = Version: RFC 1889 Version (2)
..0. .... = Padding: False
...0 .... = Extension: False
.... 0000 = Contributing source identifiers count: 0
0... .... = Marker: False
Payload type: ITU-T G.729 (18)
Sequence number: 611
[Extended sequence number: 66147]
Timestamp: 3292345225
Synchronization Source identifier: 0x0bd8775f (198735711)
Payload: f8031a1c004ad95ef85afcb74d42d9ca21dfbb97