I am having a problem with CLIP issue from India. The 1st digit is always missing regardless of changes in cadence values.
Any help

My crystal ball is a bit dusty… please give more information.
Is this inbound SIP or ISDN / POTS?
If ISDN then you will perhaps need to set the national / international prefix in zap/dahdi settings and possibly the pridialplan= too.
If only via SIP then it is possibly the provider you are using is not passing the correct digits and you may have to modify them on the inbound route.

Sorry about missing out that the inbound is POTS and uses dtmf.
The setting in chan_dahdi

In POTS we have four operators and the number is 10 digits also for mobile operators we have 10 digit numbering plan and four operators, the first digit may be 7 or 8 or 9 which is lost, it captures the last 9 digits.

hope it clears up the crystal ball somewhat ;{()