Type A SIP Phones:
  • 7905, 7912,7940, 7960
  • Do not support KPML
  • Do support SIP dial rules (SIP dial rules are configured in CUCM and downloaded to IP phone at boot time)

Type B SIP Phones:

  • 7911,7941,7961,7970,7971
  • Do support KPML
  • Do support SIP dial rules

Type A SIP Phone: No Dial Rules

  • Type A phones with no dial rules do not deliver a dial tone to the calling party when the calling party goes off-hook with a headset, speaker phone or handset
  • All digits are sent after the user completes dialing and clicks the Dial softkey in SIP INVITE message to CUCM for digit analysis (enbloc)

Type A SIP Phones: Dial Rules

  • Emulate the functionality of SCCP phones
  • When a user goes off-hook, dial tone is played by the phone
  • Digits are processed against local SIP dial rule and decided if the call can be permitted. Then, the digits are sent enbloc to CUCM using SIP INVITE without the need t0 press the Dial key
  • If a dialed pattern does not match a SIP Dial Rule, the user can press the Dial key or wait for inter-digit timeout
  • If a particular pattern is recognized by the phone but blocked in the dial rule, the call is immediately ended. The user will not receive a reorder tone, but the session will be ended.

Type B SIP Phones: No Dial Rules

  • Emulates similar end user experience to that of phones running SCCP using KPML messages  to report user activities to CUCM
  • SIP NOTIFY message is used to send every KPML event(user input key pressed) to the CUCM
  • CUCM then performs digit-by-digit analysis to recognize partial patterns as the user dials them
  • Therefore, once the route pattern match is found by CUCM, CUCM provides a call progress indication (either a ringback tone or reorder tone) after dialing the last digit, without having to press the Dial softkey

Type B SIP Phones: Dial Rules

  • Digits are processed against local SIP dial rule and decided if the call can be permitted. Then, the digits are sent enbloc to CUCM using SIP INVITE without the need t0 press the Dial key
  • If a dialed pattern does not match a SIP Dial Rule, the user has to wait for inter-digit timeout before the SIP NOTIFY message is sent to CUCM. Users do not need Dial softkey clicked to indicate the end of dialing
  • But, when on-hook dialing is used, users can click Dial soft key at any time to trigger sending of all dialed digits to CUCM in one SIP INVITE message
  • If a particular pattern is permitted by the phone but blocked by CUCM, the user must dial the entire dial string before receiving an indication that the call is rejected by the system

SIP Dial Rules Advantages:

  • Network BW is conserved as the number of signaling message exchanged btw IP Phones and CUCM across the network is reduced (Unlike SCCP Phones)
  • Less CUCM processor and memory overhead (Unlike SCCP Phones)
  • Provides processing and signaling benefits

SIP Dial Rules Disadvantages:

  • Loss of reorder tone for pattern rejection in Type A SIP IP Phones

Pointers:

  • SIP devices support enbloc dialing by default
  • SCCP phones support digit by digit addressing method
  • Trunks and ISDN PRI’s send their digits enbloc by default but they can both be configured for overlap sending and receiving, allowing digits to be sent one by one over an ISDN PRI
  • KPML is a Cisco standard
  • Type A phones use Enbloc and SIP Dial Rules methods of addressing
  • Type B phones use KPML and SIP Dial Rules methods
  • Unlike Type A IP Phones, Type B IP Phones do not need the Dial softkey at any time to trigger  the sending of all dialed digits to CUCM in one SIP INVITE message/to indicate the end user input
  • Dial rules should be configured more restrictive than calling restrictions applied at the CUCM call-processing layer