SIP PSTN multi country call routing for service numbers

[James Hawkins]

Hi,

I have a CUCM upgrade project for a company with offices in several European countries.

These offices currently have local voice gateways with ISDN PRI circuits but it is planned to replace these with a centralized SIP service.

I am fine with setting up call routing for standard destinations such as landlines and mobiles which can be expressed in E164 format but I am a little confused on how I should set up service numbers such as 112 which is the European standard for emergency services.

RFC 3996 suggests that service numbers should not be prefixed with the country code and instead a "phone-context should be used.

For example, when setting up emergency routing for The Netherlands I should not use +31112 but should use something like 112;phone-context=+31

I cannot find any documents that specifically discuss this so I would like to know how others have handled this requirement.

By the way I know that emergency dialling via centralized SIP is not ideal - I also need to cover other types of service numbers.

[Roger Kallberg]

You will need to discuss this with your service provider for the centralised SIP service. They need to provide information about how they handle this in their service.

[James Hawkins]

Thanks Roger,

I have got a response from the provider. For emergency calls they route the call based upon the CLID. For other service numbers they need them to be prefixed by the + and the country code. This goes against what the RFC recommends but seems to work.

I was wondering whether I was missing some SIP profile magic but phone-context does not seem to be implemented as I thought it might be.