High latency causing problems... and frustration w...

Question

I have a femtocell that requires the latency on any single hop on the internet to be less than 240ms, any longer than this and it drops my phone call. On contacting the supplier of the femtocell, they asked me to use Traceroute to see how long the path to a server was (I used Google.com) and many of the hops were over 240ms, some as long as 4922ms.
On scanning this forum, there are other users out there (mostly gamers) who are suffering from latency problems. Has anyone had any success resolving the problem? I can send copies of the Traceroute outputs that clearly show high latency between routers with addresses such as interconnect2-gig1-0.manchester.fixed.bt.net, core2-pos0-6-1-0.ealing.ukcore.bt.net and core4te-0-7-0-0.telehouse.ukcore.bt.net, to anyone that may be able to help.
The best I've so far had from BT is that:
- It's a problem with the femtocell supplier: no, the supplier requested from ISPs their longest expected latency prior to releasing the femtocell and set the timeout to be equal to this
- It's a problem with my Mac mail: the fact that I use a Mac has absolutely nothing to do with network latency
- There's interference between my mobile phone and my wireless: this isn't the case (I'm a wireless communications engineer by background) and, if it was, almost no-one would be able to use mobile phones given the number of wireless access points in homes and offices.
Every time I get a call from the call centre it's someone different, who doesn't understand the problem, doesn't know what a femtocell is and hasn't read the notes which clearly state that I want to be called on my mobile, not on my home phone. It's looking like my best option may be to try to find another ISP who doesn't have this problem.

Answer 1

I think you have the result of what is maybe a 2 fold issue.
Femtocell technology is still a relatively new technology as you;ll  know from your job.
If you think about the security issues of running a femtocell, that;s to say what it actually has to fulfil,
Security for femtocell networks spans several distinct requirements. The service provider must authenticate users as they arrive on the network. The RF link between the handset and the femtocell must be secured for both user and control plane traffic. And lastly, the mobile network traffic must be placed into a virtual private network as it traverses the wired ISP network to ensure that the traffic is protected while transiting this public network and only authorized users can forward traffic to the mobile operator's network.
There is however one very important element of femtocell security which makes the implementation significantly more complex. This relates to latency as you say, which must be carefully managed especially for applications such as VoIP/SIP. Compounding this challenge is the unknown nature of the latency across the ISP network, which has resulted in service providers requiring latency in the femtocell to be minimized, as you say.
If you add to that the fact that the BT broadband system is based on an algorithm packet handled system to ensure data quality across maybe noisy telephone lines, it all compounds to add to the problems of the running of the femtocell.
In other words if you have a highly error corrected and interleaved broadband line, it's not going to help the femtocell out by adding additional latency to what is already a fairly complicated situation where data handling is concerned....