Last week I discussed Caller-ID Spoofing: Legislation as a follow up to a prior post: SIP Trunking: WARNING Caller ID. Now I want to discuss the value of Caller-ID and why you may want to preserve Caller-ID presentation in, out and across your network and then look to moving beyond the old services to new opportunities. SIP trunking may be the right vehicle to get you there.Caller-ID is a feature that we sometimes take for granted. Implementing SIP trunking into your network may require a little extra effort to preserve how your Caller-ID features worked prior to the change, and these little details do matter.
Our SIP gateway allows options to present User Names, PBX CLIP or Authentication ID as the Calling Line Identification Presentation (CLIP). These optional settings affect how outbound CLIP is made to called parties. Another option allows the use of the SIP-URI (Uniform Resource Identifier). These are important options that permit manipulation of the SIP header message containing the Caller-ID information. While inbound Caller-ID is usually pretty straightforward, preserving the Caller-ID for outbound calls that include call transfers or trunk-to-trunk connections--translating which Caller-ID that the called party ends up receiving does make a difference. Subtle options used in treatment of calls can change how the called party sees the call. Transferred calls delivered to another party are going to show either your company Main Billed Telephone Number (MBTN), the user CLIP that made the transfer, the original caller's CLIP or "Unknown."
User Names option in our system reflects the identity established for the SIP trunks with the provider and this is the MBTN and is a default followed by the user extension names. The SIP message header is modifiable by using optional settings. PBX CLIP replaces the MBTN with customized per extension user settings. The two data fields for extensions are extension name and CLIP ID and both are delivered in CLIP. For CLIP ID we set the user DID number or the company MBTN. The flexibility is being able to insert other numbers such as business cell phones for telecommuters. For tenants this is also important in showing the Caller-ID of the appropriate company.
Two additional features modify system behavior properties for ISDN PRI and SIP trunking. The options are "Send CLIP of CO Caller when transferred" and "Send CLIP of CO Caller when ICD Group with Cellular Phone." The first option sends the CLIP of the held party to the transferred party. The second option sends the CLIP of the caller that is transferred trunk-to-trunk (PRI-PRI, SIP-SIP, SIP-Cell) to a cell phone user/member of an Incoming Call Distribution (ICD) Group. Enabling both of these features sets the system behavior for CLIP and by changing the gateway to PBX CLIP the original Caller-ID of calling parties is preserved when transferred in and out of the system/network.
Then we must discuss COLP (Connected Line Identification Presentation) and COLR (Connected Line Identification Restriction) across the network. These features, when user enabled, allow each station user to present their public or private (extension) numbers (COLP) or to not show any telephone number representation (COLR). For telemarketing concerns, call center operations and large enterprises, these decisions will be based upon corporate policy.
An interesting twist is what to use for inbound treatment: CLIP or Calling Name Identification Presentation (CNIP)? The default thinking is normally CLIP (with numbers) but using CNIP (with names) may simplify the number of entries in a database or centralized call processing. Traditional PBXs and even IP-PBXs normally use CLIP for automated attendants doing lookups, but it would be nice to see some creative juices flowing with CNIP lookups.
Our automated attendant/voice mail uses Caller-ID based routing and between IP-PBXs that are networked. CLIP sent to another IP-PBX across the network might hit databases that have Caller-ID records of customers stored to ensure that they auto lookup and ring directly to specific agents, bypassing the automated attendant/IVR tree completely. iPhones remain another area to inspect because the iPhone receives CLIP and looks for matched address book entries to display your address book entry. When there is no match it defaults by showing just the phone number, "Wireless Caller" or "Unknown." The UC client screen pops are using CLIP but again, think about the number of entries, either user driven or system administrator controlled, that take Caller-ID into account to pop screens or perform simple routing to give customers faster service (priority routing).
There's a lot of creativity that remains un-charted. Couple SIP with SIP headers and Caller-ID and database lookups all together and you can create across a private network an entire dialing system just to lookup widgets and screen-pop the employees or even callers with a spec sheet or document. Then for the iPhone and Blackberry enthusiasts I think more opportunities exist too. Companies wrestle with providing self-service, and the possibilities of using SIP combined with the company dial plan presents new ways of delivering matched content to the caller. Whenever you muster up courage to venture into your call flow mapping exercises, don't forget about Caller-ID, else you may end up CLIP-flopping. I enlisted my buddy Graham Francis, CEO of The SIP School and we talked about some of these possibilities.
Caller-ID is an effective tool that can be used with a dialing plan--remember, appending/prepending or adding/deleting digits that branch off of AA/IVR trees tagging calls is a possibility with SIP trunking. Graham was quick to point out that SIP trunking must eventually move beyond common G711/G729 for instance, and provide HD. Then there are numerous opportunities for the carriers to sell more, including encryption or filtering. Moving into other scenarios with SIP is challenging because as Graham said to me, "watching out for what's missing" is another consideration for those contemplating SIP trunking. More opportunity I believe exists with SIP trunking, and adding intelligent call routing flags to calls destined for the enterprise could make a better overall cradle to the grave experience for callers. Way back when three PDP11's were hot (Calls, Reports, Standby), playing call announcements to agents such as "Sales" was pretty cool. Today providing what callers want before you even answer the call is cooler.
