Thursday, 24 November 2011

UK PSTN Route Patterns

Using the international dial plan installers from Cisco and the @ symbol for route patterns has two major shortcomings:
  1. You can't easily see what numbers can or can't be dialled
  2. You're at the mercy of Cisco updating it, which can lag a long way behind changes in the dial plan
So whenever I do a Communications Manager installation I manually define the PSTN access route patterns. Ofcom do publish the specifications of the UK Numbering Plan online, below is the route patterns for a simplified version.

Route Pattern Description
00! International dialling
101 Non-emergency police services
111 Non-emergency healthcare services
112 Emergency services
123 Talking clock
999 Emergency services
116XXX Services of social value
118XXX Directory enquiry services
08001111 ChildLine
08454647 NHS Direct
0[12]XXXXXXXXX Geographic area codes
03[0347]XXXXXXXX Nationwide numbers at geographic rates
055XXXXXXXX Corporate numbers
056XXXXXXXX Location independant electronic communications services
070XXXXXXXX Personal numbering service
07[1-9]XXXXXXXX Mobile/pager services
0[58]0XXXXXXX10-digit Freephone
080XXXXXXXX Freephone
082XXXXXXXX Internet for schools
084[3-5]XXXXXXX Special services basic rate
0870XXXXXXX Non-geographic numbers
087[1-3]XXXXXXX Special services higher rate
09XXXXXXXXX Premium rate services


  1. Uk 01 numbers can be 9 or 10 digits in length. How do you cater for this?

  2. Route patterns for 9 or 10 digits can be implemented, but then CUCM will wait for additional digits until either 11 digits are dialled or the inter-digit timeout happens, as there's multiple possible matches. The inter-digit timeout can be avoided via en bloc dialling or route patterns with a terminating digit (e.g. #), but both these methods require changing user dialling behaviour.
    With CME there's no option but to use T for inter-digit timeout, as dial-peer matching logic would always trigger the 1st match, which would be the 9 digit pattern.