1. Phone numbers and dial strings
Rohan Mahy & Brian Rosen •

2. Phone Number vs. Dial String
Global Number: tel:
Local Number
tel: ;phone-context=cisco.com
Context
Dial String 8p

3. What we agree on
Don’t mess with userparts of SIP URIs if they are not yours
Some SIP domains have numeric usernames/userparts. Sometimes these conflict with phone numbers and dial strings.
Some folks will need a user=phone parameter
Phones and other UAs having a dial plan is good thing

4. We agree: continued
User=phone parameter in SIP means that the userpart of a SIP URI is a valid RFC2806bis tel: URI
tel: URI can be a global number, or a local number with phone-context:
tel:1234;phone-context=example.com
some devices are really stupid and need a proxy to translate dial strings for them. the proxy needs to know if it should do digit map translation when it gets a request

5. Where we disagree:
How do you keep dial string contexts and local phone number contexts separate?
Proposal 1: Use separate contexts. Each context handles either dial strings or local numbers. Proxies need to be configured to know which is which:
tel:123;phone-context=acme.com vs. site.acme.com
Proposal 2: New user=dialstring parameter. Userpart is an RFC 3601 dial string with a context userpart parameter. Can have pause and wait:
;user=dialstring