# Data call in with mISDN & Asterisk

**URL:** <https://community.asterisk.org/t/data-call-in-with-misdn-asterisk/24897>\
**Category:** Asterisk Support\
**Created:** [January 9, 2009, 5:15am UTC](https://community.asterisk.org/t/data-call-in-with-misdn-asterisk/24897 "2009-01-09T05:15:41Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![parazhang](https://avatars.discourse-cdn.com/v4/letter/p/3ab097/32.png) [@parazhang](https://community.asterisk.org/u/parazhang)\
**Post date:** [January 9, 2009, 5:15am UTC](https://community.asterisk.org/t/data-call-in-with-misdn-asterisk/24897/1 "2009-01-09T05:15:41Z")

</div>

Hi,all:

```
I set up one Asterisk with mISDN,and let others using the data call in feature so that can go to the internet through it,Now I finished it successfully,it can let users dial in with ppp encapsulation,get the ip address and browse the internet.
Anyway,a little confused:

As I used PPP,why must I set the HDLC=yes in the configuraion?

```

We know that both PPP and HDLC are layer 2 [protocol.Is](http://protocol.Is) it just a asterisk magic switch or the data encapsulation is really using HDLC way?

Thanks in advance.