PlusNet Fibre - Static IP - Cannot Access from Three Mobile Network

[#1]

Hi,
I've posted this as a question to support but wondered if anyone else has had any issues similar to this?
So I signed up to PlusNet last week, all is well with the connection and 99% of it seems good, but the 1% is bugging me.
I've got an MS Exchange Server (as well as many other services) running on the static IP with rDNS, this works completely fine but for some reason I cannot access this IP at all from Three Mobile.
At first I thought it was down to Three but doing a Trace Route shows the failure at the router/gateway just before my Gateway...
Here is an example trace route performed on Three Mobile Broadband from a Windows 7 machine:
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
C:\Users\administrator>tracert sub.domain.org.uk
Tracing route to ***MYDOMAIN*** [MY IP ADDRESS]
over a maximum of 30 hops:
1 1 ms 2 ms 15 ms 3.home [192.168.10.1]
2 99 ms 69 ms 59 ms 172.23.227.1
3 44 ms 49 ms 49 ms 172.30.146.163
4 53 ms 50 ms 48 ms xe-8-2-0.man11.ip4.tinet.net [141.136.99.97]
5 46 ms 58 ms 59 ms xe-7-0-2.lon10.ip4.tinet.net [141.136.107.9]
6 59 ms 68 ms 49 ms ae8.edge4.London.Level3.net [4.68.111.25]
7 53 ms 58 ms 59 ms vl-3508-ve-122.csw1.London1.Level3.net [4.69.166
.14]
8 106 ms 79 ms 80 ms ae-57-112.ebr1.London1.Level3.net [4.69.153.117]
9 93 ms 79 ms 89 ms ae-44-44.ebr1.London15.Level3.net [4.69.167.29]
10 78 ms 118 ms 69 ms ae-1-3.edge4.London2.Level3.net [4.69.141.190]
11 76 ms 98 ms 89 ms ae-0-11.edge3.London2.Level3.net [4.69.200.125]
12 132 ms 79 ms 79 ms PLUSNET-TEC.edge3.London2.Level3.net [212.187.20
1.214]
13 101 ms 79 ms 79 ms te3-1.pcl-gw01.plus.net [212.159.0.205]
14 72 ms 59 ms 89 ms link-a-central10.pcl-ag04.plus.net [212.159.2.17
3]
15 * * * Request timed out.
16 * * * Request timed out.
17 * * * Request timed out.
18 * * * Request timed out.
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 * * * Request timed out.
23 * * * Request timed out.
24 * * * Request timed out.
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
C:\Users\administrator>
It wont go any further...
Now to confirm, I have checked the router and have no specific IP address blocking, it works fine from BT/PN/Sky/O2/Vodafone
Its rather annoying as most of my family are on Three and no one can currently access email until they get home or connect to WIFI.
A friend also has a static IP address on PlusNet and his is fully accessible from Three, but it routes via different PlusNet gateways...
Any ideas?
Thanks

[#2]

That trace doesn't prove you can't access it, just that it isn't responding to pings.  Is there any logging on the exchange server to show it's seeing the incoming mail traffic?

[#3]

traceroute on a PN network completes though?

traceroute to **.66 (***.66), 64 hops max, 52 byte packets
 1  10.0.1.1 (10.0.1.1)  1214.975 ms  1.245 ms  1.188 ms
 2  lo0-central10.pcl-ag03.plus.net (195.166.128.184)  18.921 ms  17.561 ms  17.123 ms
 3  link-a-central10.pcl-gw01.plus.net (212.159.2.168)  17.194 ms  19.072 ms  16.874 ms
 4  xe-10-2-0.pcl-cr01.plus.net (212.159.0.200)  17.278 ms  17.104 ms  39.411 ms
 5  ae1.ptw-cr01.plus.net (195.166.129.0)  26.343 ms  21.786 ms  17.011 ms
 6  ae1.ptw-cr02.plus.net (195.166.129.2)  16.260 ms  17.451 ms
    te8-6.ptn-gw01.plus.net (212.159.0.117)  17.109 ms
 7  te8-6.ptn-gw02.plus.net (212.159.0.119)  17.534 ms  17.913 ms
    link-a-central10.ptn-ag04.plus.net (212.159.2.141)  20.964 ms
 8  link-b-central10.ptn-ag04.plus.net (212.159.2.143)  18.804 ms
    mail.******.org.uk (*****.66)  28.390 ms
    link-b-central10.ptn-ag04.plus.net (212.159.2.143)  19.230 ms

if I've got the right IP address..
It also completes a trace on t-mobile 3G signal.