H.323 controlling pots or digital ?

[Jonn cos]

Hi all.

I have read somewhere, that pots dial peer (FXS, FXO) are also controlled by h.323, i checked on router using debug, but i couldnt see any messages relating to h.323 when i made the call to analog phone.

have i mis read it or misunderstood it ? can someone shed some light on it ?

[Paul Jones]

The H.323 code in IOS does not control non-IP telephone interfaces.  There is separate code that manages each of those interface types.  H.323 is just one one several application protocols that interfaces internally with the code that manages those non-IP interfaces.

[Jonn cos]

Sir kindly tell me what you mean by seperate code ? is that code also part of some version of IOS ?

[Paul Jones]

By "code", I am referring to software inside the router.  Each of the VoIP protocols (e.g, H.323 or SIP) and telephony interfaces (e.g., FXS or ISDN) has software associated with it that implement what is required for that particular protocol or interface.  The H.323 software only does what is needed in order to ensure that H.323 signaling is handled properly.

Each of these separate software components communicates with each other in order to enable an H.323 call to originate and terminate on an FXS port, for example.  However, it is not the H.323 code that controls the FXS ports, which was your originate question.

[Jonn cos]

Sir, you have hit the root i must say. this is what i really wanted to ask,

Why would i need h.323 call to originate and terminate on  FXS port ? i mean what is the meaning of this statement ? this concept is new to me, let me rephrase it

" H.323 call on a FXS port, what does that mean ?"

Pls guide me

[Steven DiStefano]

FXS Ports in H.323 Mode

FXS ports on platforms that cannot enable SCCP supplementary features can use H.323 mode to support call waiting, caller ID, hookflash transfer, modem pass-through, fax (T.38, Cisco fax relay, and pass-through), and PLAR. These features are provisioned as Cisco IOS voice features and not as Cisco Unified CME features.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmebasic.html#wp1069305

[Paul Jones]

Jonn,

There's no such thing as an "H.323 call on an FXS port".  The FXS ports are ports into which one might connect a traditional analog prone.  When you lift the handset on your phone, you expect to be able to place a call.  That's where the VoIP protocols (e.g., H.323, SIP, MGCP, SCCP) come into play.  So, you could pick up the handset and dial "1234", for example, and that might result in using H.323 on the IP side to place a call somewhere.  So, that might be what someone is referring to when they say of "H.323 call on an FXS port".

In any case, there are two sides to all phone calls.  Most often, there is a legacy telephony interface on one side (e.g., an FXS port or ISDN PRI) and an IP-based protocol on the other (e.g., H.323 or SIP).  The router "glues" these together internally through software, but each interface implements its behavior indepenently from the other interfaces.