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SIP Transaction Timers
The timers of the tm module can be confusing and normally you do not have to (or should) tweak timers except the `fr_inv_timer` (controlling "how long to ring"). The table below gives an overview of the timers that can be changed from SER configuration file and their relationship to the timer names in RFC3261 and how/why you would want to change it.
Starting in SER 2.0 the timer implementation has been completely
rewritten. The timers are now controlled in milliseconds and (not in seconds
as in SER 0.9), for example
modparam("tm", "fr_timer", 30000) # default value of 30s.
Timers have a resolution of 1/TIMER_TICKS_HZ. This is by default 62.5 ms. Thus, the timer can fire every 62.5 ms. Note that this also is the error interval (they can fire anywhere in a 62.5 ms interval from their "theoretical" expire point).
