RTP Streams from Wireshark

[ilana_ilana]

Based on following discussion, it seems one can easily hack the voip calls within organization. 

https://supportforums.cisco.com/discussion/11517891/how-save-rtp-streams-wireshark-and-play-it-using-application-called-audacity

I haven't tried what mentioned in discussion but if its true, this will be a downside for sales to suggest cisco voip solution.

What should be the reasonable answer for this hitch for the customers.  Would appreciate if any one can comment on my concern.

Regards

[Mohammed al Baqari · Accepted solution]

This isn't limited to Cisco. This is applicable for any RTP stream being from Cisco. Avaya, Lync, etc. I have tested this with Avaya.

What you can decode is G711ulaw only. There is an online tool to decode G729ar8 as well. Other than that you can't decode audio codecs unless you spend massive amount of time creating decoder for complex codecs such as G722 or ilbc. These are considered high complexity codecs and need lot of processing and coding.

The workaround is to use encrypted RTP but this isn't limited to Cisco as mentioned earlier. This is applicable to any RTP stream from any vendor using standard codecs.

[ilana_ilana]

Thank for reply Mohammed.

The most favored codec I have seen at several places are either G.711 or G.729. I haven't seen G.722 and ilbc codecs configured over LAN or WAN.

As G.722 codec is complex and more secure, is it recommended to use with latest IP Phones 78XX, 89XX, DX650, DX80 ? Are there any limitation of using G722 codec with Unity Connection, IM&P or PSTN calls ?

[Mohammed al Baqari]

G722 and iLBC are the next gen codecs. G722 provides much better quality than g711 with same bandwidth. The drawback that its not supported by mgcp and its high complexity codec.

On the other hand ilbc consumes double the bandwidth of g729 but is a way better in handling lossy links and packet loss. Again high complexity codec.

Regarding cuc both g722 and ilbc are supported.  but practically they don't work well. Since they are high complexity codecs they consume lot of cuc resources to convert them to pcm to be stored in cuc database. In short I don't recommend using them with cuc.

Regarding imp, works flowless expect jabber 9.7 (2) which doesn't support ilbc and needs xcoder to convert to g729

[ilana_ilana]

Thank Mohammed

And what about PSTN GW's ?

Our client is using H323 GW and having several voip and pots dial-peer. Do we need transcoder on gw ?

[Mohammed al Baqari]

h323 support g722 natively. No need for xcoder