calls as well as all commercial calls. A telecommunications trunking system enables many clients to share a stan- dard set of telecommunication lines, or frequencies, to access the telecommuni- cations network, in much the same way as the roots and branches of a tree share a common tree trunk.
As such, Fort Leonard Wood served as the test bed for I3MP and its project partners to identify and overcome numerous chal- lenges, learning valuable and sometimes difficult lessons. Te experience will help the Army move forward with the deploy- ment of VOIP using AS-SIP.
WHY VOIP? Te maturity of IP technology, the increasing competition among internet service providers and the improved net- work security offered by IP technology provided compelling reasons for Army installations
to transition. But AS-SIP
was not a simple solution to install for the first time. While it is a better, faster and cheaper technology than TDM, AS-SIP
SURVEYING THE SYSTEM Brendan Burke, right, product manager for I3MP, tours Fort Leonard Wood’s new voice telephone service in December. The installation capability set modernization, a four-year effort, moved approximately 19,900 users to an IP- based communication system and pointed the way for other Army installations to transition to a voice architecture for reliable installa- tion communications offering mobility, voice mail and caller ID. (U.S. Army photo by Scott Sundsvold, I3MP Strategic Communications)
is not widely understood. A scarcity of the necessary technical knowledge, skills and expertise within both the public and private sectors has complicated the effort.
AS-SIP, based on the commercial stan- dards for the Session Initiation Protocol, is the DOD standard signaling protocol used on information system networks that provide end-to-end assured services. Using IP networks, AS-SIP enables inter- net telephony for voice and video calls, as well as instant messaging, in much the same way as a smartphone.
THREE PROBLEMS FOUND On a VOIP telephone system, a phone call is technically an “AS-SIP session.” To avoid confusion, this article will refer to an AS-SIP session as a “session call.” During Fort Leonard Wood’s transition from TDM to IP, I3MP identified three things that can go wrong when initiating an AS-SIP session—that is, when mak- ing a session call. (Te specific reasons for why a session call fails are too complex and varied to describe in detail.)
• No call: User A tries to invite User B to join a session call, but the invita- tion is not completed.
• Failed call: User A invites User B to join a session call, but the network never initiates the session call, so it is not made.
• No audio: User A initiates a success- ful session call with User B, but User A is not able to hear User B, or vice versa. Or User A initiates a successful session call with User B, but neither user can hear the other.
RECOMMENDED RESOLUTIONS When AS-SIP receives an invitation to join a session call, an AS-SIP message responds with an interpretation of a cor- responding request and a receipt. When protocol failures happen, error messages occur. Tese error messages are useful for troubleshooting.
In the case of the three identified issues, the only error message sent was “488 Not Acceptable Here,” which does not define
HTTPS: / /
ASC.ARMY.MIL
73
LOGISTICS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168
